I am looking into buying an RO system and I'm thinking there has to be a way of DIYing one out of parts. It's basically a series of canisters with an inlet and outlet daisy chained through other canisters. Anyone done this or know how? Are the tops that the canister connects to available? I can get water line, fittings, the clear part of the canister, obviously the filters, yada yada yada, but can't find the tops to to the canisters. Any input would be great. Thx!