I'm sure there are some DIY solutions to this, but I'd probably just grab a cheap Sodastream or another like it. The biggest long term cost of those devices is getting refills of the tiny CO2 tanks - which you can do easily and cheaply from your big tank. Hell, I've thought about getting a big CO2 tank JUST for this reason.
There's adapters out there to do this. Something like: https://smile.amazon.com/Conversion-Adapter-SodaStream-Paintball-Canister/dp/B0798DTRJQ