I started rummaging around through my stuff looking for different foamy products that could be used as a backing for the pins. I tried some foam insulation and ear plugs but they were too squishy and Styrofoam deteriorated a little each time I poked a hole in it. Then I came across some foam that is used to make rubber stamps and I was pretty sure that it work, but I needed a thick piece. Unfortunately, all the pre-cut shapes at Michaels were thin, but then I found a 9 x 12" sheet that is 1/4" thick. I purchased one sheet for $.99 and headed home to experiment.
It's really easy to cut through the foam with your rotary cutter. I cut a strip that was 1/2" wide, then cut 1/2" pieces from the strip. After cutting several of these. I found my flower head pins and stuck pins into the foam. Yay . . . it works great, but if you look really close to the picture above. The pin is almost inserted the full length of the 1/2" foam piece. I decided it would be a good idea to cut a few different sizes and try them out to see what I liked best.
You can see two of the pins and foam above. The piece on the left is a 1" square piece of foam. I only did a couple this size and quickly decided that it blocks my view and I wouldn't like these all over my quilt.
Here is a close-up showing you how I bent the flat flower pin to make it easier to get through your quilt layers. I haven't actually quilted with the pins yet (I just finished inventing this 10 minutes ago), but it looks like it's going to work just fine. So far, the size that I like the best is 1/2 x 5/8" because there's a little extra wiggle room in the length. I'll get at least 100 foam pieces from one 9 x 12 sheet. Not bad!
Let me know if you use this pin basting system and like it!