ER 20 Collet Holder

Here lies both my first upload on this site and a collet holder of the ER 20 variety. It Holds 20 ER20 collets. Why 20? I'm not really sure since I only have 7 of them. I can scale them for other sizes if need be. Just let me know.
Recommended Hardware:
4x 16mm M5 Button-Head bolts (I used 16mm M5x1.25's but just make sure the inserts match the bolt thread)
4x 6mm M5 Heat set inserts
Drywall anchors and bolts

Quick note: I almost always drill or mill out holes but if it works as is cool beans!