This is embarrassing:
It's not just that I'm not the first one to come up with this idea for separating SPP and LPP brass. Other, probably many others, have already designed this and shared it on line.
What's embarrassing is that about 5 years ago, I down loaded someone else's design and actually printed it. There's being 10x10 block with square holes, so I can claim a little more elegance in that mine has rounded, chamfered holes. Yes, I found it this morning in my Storage Cabinet of Stuff.
I'm keeping my SPPs. Hoarding? At some point down the road I might have enough that I can have a special loading session with just SPP.
Yes so many things you can make for yourself. My .45 Mooner was downloaded and printed in 3D. Now that I'm actually using it, being plastic, I'm printing a backup with PETG, a tougher, less brittle filament, instead of PLA that I used on the first print. Also adding a base so it sits flat and doesn't rest on the bolt head.