Oil catch can moditication

Okay
I have reviewed a couple of others use of using oil catch can that is used with positive crank check valve //

I have the following concerns
Size of catch can small/big
Material type all metal/clear abs
inline or other

Currently consider small inline clear plastic style aka same as air compressor air /oil separator style so quick visual inspection and drain can be relative straight forward

maybe this
1/4" Air Line Oil Water Trap Separator Filter For Compressor Spray Paint Tools | eBay