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!!
cheers
Bill