DIY Softbox from an umbrella

Step 5 Gather additional fabric in the umbrella shell

Now re-attach the string/threads that hold the softbox in a square shape and the proper dimensions. Here I would encourage you to tie it slightly undersize (because there is a lot of stretch in the seam and fabric. So for a 28" finished softbox, tie it in a 26" x 26" square.

Now gather the extra fabric between the 4 legs. Three of them will need to have this extra flap sewn shut (leaving the gather on the inside). This pretty much requires some hand sewing, because its impossible to get a sewing machine inside the umbrella. If you want an easier time sewing, this can easily be done if you decide you don't mind having the gathers/seams on the outside of the finished softbox.

Only sew 3 or the 4 gathers. The 4th is where the lightstand will go, so you need to cut and hem about a 12" slit in one side.

Also measure about 4" in from the 4 points of the umbrella where the ribs where removed, and trim off this extra "point" of fabric, making a clean square profile to the lip of the box.