The foam was leftover from a laptop shipping box. It had the bumpy egg-crate pattern.
I made a quick hot-wire-foam-cutter using about 8 inches of 28g NiCr wire and about 8 VAC from a Variac to "plane" the foam to the thickness I needed. This process removed the egg-crate bumps.
To make the holes for the collets and nuts, I used a simple hole-cutter punch hammered through the foam into a soft wood backer.
The divots for the MT1 shanks was just done with a razor blade.
The punched holes came out perfectly and the planed surface is the face side in the photo above.
I use both ER32 and ER11 collets. There is a full metric set (about 18 or 19) plus a few imperial ER32, and full sets of metric and imperial ER11, maybe 20 or 24 in total. I got some pvc water pipe from the hardware shop, cut to length using a simple jig on the bandsaw, they ended up as approx 1.5" o/d x 1.25" long for the ER32, and 5/8"o/d x 5/8"long for the ER11. The hardest bit was deburring. Then stuck together using plumbers primer and glue, left over from a previous job. The pvc pieces were stood in a drawer (hole side up!!) whilst gluing to ensure that the assembly was fairly flat. Then the whole lot was placed in a steel toolbox on the rubber mat and filled up with collets. The whole thing was done in an hour or two, and only cost a few dollars.
As they say in the classics....Easy peasy!!
Nice storage is always handy for locating the bit you need when you need it
My er32 collet set came in a wooden box with an mdf fitted grid of holes, amazingly (to me) i havent had a rust issue with it, although it has picked up a bit of oil which might help with that. Maybe they used a low acidity mdf?
Always tempted by an er11 for all the times the 32's nut gets in the way.