Its a versatile portable system of modifiers for your strobe. I've already started my own set of DIY modifiers from ideas on DIY Photography, and here on Instructables, so I didn't need a whole system. I also use Velcro, but I didn't like leaving sticky adhesive on my strobes. I also didn't want to spend $10 per strap.
Here I've used some sticky back velcro, and tennis grip overwrap that I already had on hand. Its cheap enough to make them for all your strobes, and probably have some for your friends too.
Step 1: Materials
1. Overwrap for tennis raquet grips. - This one happens to be Prince, but any thin cheap overgrip will work.
2. Adhesive backed hook and loop fastener. - I had some genuine Velcro on hand.
About 10 in. / 260mm of the loop side of the fastener,
about 2.5in. / 60mm of the hook side of the fastener,
and about 7.5in / 200mm of the overgrip tape.
You can adjust these to the size of your flash head.
Step 2: Tape the tape...
Then peel off most of the backing on the loop side of the Velcro and stick it down to the back of the overgrip tape.
Step 3: Flip and tape
Then stick the loop side of the Velcro onto the back of the exposed back of the loop side.
Step 4: Trim
Also trim off any extra width of the overwrap.
To make sure it was all stuck together, I used firm pressure to run the side of a pen across the whole strip.
Lastly, peel off any packing film that may be on the overgrip, to expose the tacky rubber.