Instructions for building a Mini Soft Box
Copyright by Karl Zemlin 2008 - All rights reserved -

There are quite a few pictures below, so give the page a little time to load.

At the time of this writing (November 2008), I have prepared plans for two sizes of mini soft boxes.  Both sizes are designed for a Nikon SB-600 or Nikon SB-800 flash.  They should work with any flash with a 1.5" x 2.5" head.  See 2/ for photos taken of the smaller version.

The small size has a front face that is 7.5" x 10" and all the patterns can be printed on 8.5 x 11 (A4) paper.  The front face of the larger soft box is 12.5" x 17".  These patterns can be printed on 11x17 (A3) paper.  The assembly procedure is the same for both sizes.  The photos in these instructions were taken when I was building the large version.

Patterns for small version

Sized for Nikon SB-600 & SB-800 (11/2 x 21/2 head)
Foam shell
Large reflective panels
Small reflective panels
Sized for Vivtar 285 (21/4 x 33/8 head)
Foam shell
Large reflective panels
Small reflective panels

Patterns for large version

Sized for Nikon SB-600 & SB-800 (11/2 x 21/2 head)
Foam shell

Large reflective panels
Small reflective panels
Sized for Vivtar 285 (21/4 x 33/8 head)
Foam shell
Large reflective panels
Small reflective panels

The Vivitar 285 designs are based on dimensions provided by a Flickr member.  I don't own the flash and cannot confirm the dimensions or test the design.  If you build one, please let me know how it goes and if you feel any adjustments should be made to better fit the flash head.

Make sure there is no scaling set when you are printing. You can check that the patterns are the correct size by measuring the line dimensioned as 2". These should be EXACTLY 2" long on your print outs. You will need 2 copies of each pattern.

The build time for the small version I made last time was about 3 hours, including dry time for the glue.

Shopping list:

1 sheet of 2mm craft foam (typically sold in 12"x18" sheets).  The large soft box takes 3 sheets.  I used black as any self-respecting photographer would, but the amount of foam exposed to the light is so small I see no reason other colors wouldn't work just as well.  This stuff is available at arts and crafts supply stores.

White mat board. I bought the most brilliant white mat I could find. It doesn't take a large piece. I ended up buying a 30"x40" sheet of mat board for $4.

Double mat mylar drafting film for the diffuser screen.  You should be able to find this at an arts and crafts supply store - likely the same place you buy the craft foam.

Velcro squares for securing the diffuser to the soft box.

Hair ties. I bought some that have a rubber grippy spiral to prevent slipping. They work great for securing light modifiers to a flash head.

Single-edge razor blades, or other very sharp cutting tool.

12" straight edge (18" for the large size).  I like the flexible steel rules with cork backing to keep it from slipping when cutting.

White glue or woodworking glue.

Hot-melt glue & glue gun.  I used a scrap piece of plywood as a cutting board.  A soft plastic cutting board also works well if you have one large enough.

A stapler

A bit of gaff tape may come in handy

Lastly, I used a couple #10 cans of spaghetti sauce (weights) and a scrap of plywood or another cutting board for clamping the mat board to the foam while the glue dries

Ready to get started?

To keep the pattern in place while cutting the foam shell halves, you might want to staple the pattern to the foam.  I just staple one edge - that's the last edge I cut.

Start cutting the foam with the straight edge and razor blade.  The foam cuts very easily in a single pass.  Just make sure the paper is flat against the foam before you start cutting.  Again, save the stapled edge until last.

There is a short solid line near the base of the "V" in the fold lines.  You need to slit this line as shown to form the flaps that will fit around the flash head.

When you have all the cuts made in the foam, trim off the edge with the staples.

This is what the finished foam shell half looks like.

If you have the means, use a small hole punch to cut circles at the end of the straight slits for the flaps.  This is  purely optional, but it will help keep the foam from tearing at the ends of the cuts.  I have not had any trouble with the foam tearing - this is just precautionary.

Next, I trim the patterns for the mat board panels.  I trim the angled edges so they have 1/4"-3/8" of extra, and 3/4"-1" on the parallel ends.

Arrange the patterns on the mat board to minimize the amount of scrap you will need to throw away.   The mat board I bought was two sided - one side white and the other side beige.  You'll want to staple the patterns to the non-white side of your mat board.

Staple the patterns along the parallel edges.  Two or three staples along the long edge, and one on the short edge.  As with the foam, you will cut away the long edge with staples last.

You might want to cut between the patterns to separate the panels into smaller pieces.  This will make it easier to cut them down to size.

Before you start trimming the large panels, you need to mark the centerline for reference when you start gluing.  I found the easiest way to do this is to make a light cut with the razor blade.  Use just slightly more pressure than is required to cut through the paper pattern.  You just need to leave a visible mark on the mat.

Trim the mat board panels using the straight edge and razor blade.  Don't try to cut through the mat board in a single pass - make a number of light cuts - it usually takes about 8 passes for me to get completely through the mat.  Cut the angled sides first, the short stapled edge next, and the long stapled edge last.

When you get the panels all cut, you should have four mat board panels - two large and two small - and two pieces for the foam shell.

You might want to make the center mark on the large panels more visible by drawing over the light cut line with a pencil or pen.

Before you start gluing, make sure you have a weight and something to spread the weight over the flat panels.  I use regular wood-working glue to bond the foam to the mat board.  I like to thin the glue about 10-15% with water so it is easier to spread.

The assembly starts with a wide mat-board panel and one of the foam shell halves.  The photo below shows how the panel and foam fit together.    Be very accurate with the alignment of the foam to the mat board.  Where the edges come together the foam and mat should be flush.  The foam should be exactly on the center line on the mat panel.

Once you are comfortable with how things go together, spread a bit of glue on half of the mat panel.  Be careful not to use too much glue.  If it squeezes out around the edges it doesn't look good and it's very hard to clean up.

I use a credit card or something similar to spread the glue out to an even layer.

Carefully position the foam on the glued side of the mat panel.  The edge of the foam should line up exactly with mat board as described above.

Cover the glued area with a board or something similar and weight it to allow it to dry.  Be careful not to shift the foam on the mat board when adding the weight.  Let the glue dry for 20-30 minutes.

Next, glue the other foam half to the other half of the same mat panel.

The next step is the glue the other large mat panel to one of the two foam halves.

This is what things look like with the two large mat panels and the two foam shell halves.

You can now glue the first small mat panel in place.  You need to align the long edges and match the gap on both sides between the other two panels.

Weight the panel as before and allow the glue to dry

For the last panel, you'll align the outside edge of the foam with the mat board, and match the width of the gap that's on the other side panel.

When the glue is good and dry on that joint, you're ready to give the soft box some shape by gluing the last half-panel to the foam shell.  Do a dry run with this before you spread the glue to make sure you know how it will fit up.

I used a couple small piece of gaff tape to hold the seam together while I flip the soft box over and set the weight for clamping the glue joint.

Once the glue dries, the basic shell of the soft box is finished.  It's time for some finishing touches.
Cut four small pieces of foam.  Two pieces 1" x 1 1/4", and two pieces 2" x 1 1/4".  These will be glued inside the small flaps at the point of the pyramid to aid in securing the soft box to the flash head.  There's really no significance to the soft box being held flat in this shot except to show that it does fold flat.  I changed my plans on how I glued these flaps in place.

I use hot melt glue for these pieces, as the white glue is slow to dry when it's between two pieces of foam, and this glue joint needs to be flexible.  The 1 1/4" dimension on these pieces goes front-to-back.  I have the pieces extend past the end of the existing flaps by about 3/8".

I found it easiest to glue these pieces in place by applying the hot glue to the flap from the inside while I held the other piece ready to drop it in place.

The last pieces to be glued to the shell are long strips on the top and bottom edges.  These help eliminate light bleeding from behind the diffuser screen.  I cut these 1" wide and 1" narrower than the long side of the soft box, so on the large version shown here the strips are 1" x 16".

These get glued in place with white glue with 1/2" glued and 1/2" hanging out past the edge of the shell.  I use white glue here because I would not be able to spread a consistent bead of hot-melt glue 16" long and get things clamped in place before the glue starts to cool.

The final piece of the puzzle is the diffuser screen.  I use double matte mylar drafting film for this piece.  It's a tough plastic that diffuses well with minimal light loss.  It's strong enough to lie flat when it's in place and doesn't crease easily.  It's really seems like great material for this purpose.  This needs to be cut to the same height as the front of the soft box (12 1/2" in this case) and longer than the soft box is wide so it can wrap around the ends.  This piece is 18" wide, because that's all I had.  I would have made it wider if I had more.  I also cut a couple strips of mat board 1 1/4" x 11 1/2".  These will be glued to the ends of the mylar.  If you have it, black mat board might look better here since these strips will be on the outside of the soft box.

I use hot glue to secure the mylar to the mat board.  Since my mylar is narrower than I'd prefer, I can only overlap by about 1/4".  I prepared for the gluing operation to make sure both piece were positioned and held in place.

You need to act fast with the hot glue or the mylar won't stick well.  Lay down a bead of glue and stick the plastic down as quickly as you can.  If the glue is hot, the mylar will stick to it securely. 

I was not fast enough on this.  I was able to make a good glue joint by using a hot iron (Linen setting, no steam!) with the plastic down and mat board up.  Don't let the iron contact the mylar.  It will heat through the mat board and melt the glue to bond the pieces together.

Here's where I demonstrate that even the best laid plans can go awry.  I intended to glue the mat strips to the same side of the mylar.  If I were using black mat I would glue the mylar to the black side.  I like to have the glue joint on the outside.  If it's on the inside, the glue is in tension when the screen is attached.  I think it's better to have pressure on the glue joint.

I have placed four velcro squares on the mat board stips.  The location is not critical, just be consistent.  On this soft box they are 2 1/2" from the end of the mat board.  I put the hooks on the mat board.  The loops will be glued to the soft box.  To place the loops in the proper location, stick loops square to the hooks squares after you have stuck the hooks to the mat board.  Remove the backing so the loops are ready to press into place.

Carefully position the soft box shell over the diffuser screen and fold up the sides to stick the velcro to the outside of the shell.  Carefully separate the velcro loops from the hooks and remove the diffuser from the soft box.  You can now press the velcro squares securely to the soft box.

I like to trim the corners of the diffuser at a 45 degree angle once things are put together.

Here the complete screen is back in place on the soft box.

The first test shot with soft box shows that it's doing it's job.  This design is going to need a little more work.  I'm going to come up with an internal diffuser to spread the light better and eliminate the hot spot in the center.

As is is, however, the light is reasonably even.  This is taken with the soft box about 12" from the plywood pointed straight down.  You can see the edge of the soft box in the top of the photo.

In testing with the smaller soft box design I got the best results with the flip-down diffuser screen in place.  I tested with and without a Stofen dome.  The light was clearly more evenly spread and a lot brighter without the dome.

Here's another test shot using the soft box.  This is the lovely designer of this soft box, and also the hand model used for these instructional photos.  I think we caught him on an off day.  The soft box was probably about 18" -24" from my face for this shot.  Probably should have been higher, but I didn't have a light stand handy.

One final image showing the soft box on an SB-600 flash held in place with hair ties.  This larger soft box is a bit heavy and sags slightly when on the flash.  I think a bit of gaff tape may be in order when using this design on a flash.

My email address is at the top of these instructions. Feel free to email me if you have any questions.  Let me know if you find any errors or have suggestions for making the design or the assembly procedure better.

Thanks, and enjoy.