eBay

Tools -T161330 Trade 3/16" Hard Plastic Spacers 'T' (Pack of 500)

Hard plastic - does not compress
3/16” are hollow allowing thin set through
Can be used as leave-in spacer

Ox trade Tile spacer - hard 'T' | 3/16 inch | 500 pieces/bag, 3/16” spacers are hollow allowing thin set through, made in China