sabot: I found that bottles of Propel fitness water with the rim trimmed off make perfect fittng sabots for 1.5" sch40 PVC barrels, I think 3liter bottle cap also may work but I'm using them for cheap chammbers
Ammo: some of you may have a black walnut tree that drops rough green ball like objects in your yard, those are black walnuts they may not look like the edible walnuts but if you break them or let that green cover rot off you'll see, some of those smaller ones make decent fitting projectiles for 1.5"
I'll try to get some pics to show
edit:

ideal bottle I got plenty of these thanks to costco

it normally doen't fit inside but...

a little trim...

and volla perfect sabot

I had to shoot the tree to get a fresh leaf sample since the braches are out of reach
