12g to 16g CO2 canister adapter

I have a 16g CO2 duster and a lot of 12g CO2 canisters ("powerlets", i suppose) around, and I don't want to stock both sizes.The 12g canisters are a little smaller, but by inserting this plastic cup under one it fills the compartment for a 16g and works well.
It was an easy 5-10 minute print, and works well.