You could try clear PVC tube that's a tad cheaper.
With pvc you also can use standard sized couplings and hose connectors.. I once made a simple smal canister filter from 50mm pvc pipe.
This is the only picture i have of it. I no longer use it, it's replaced with a hob. But it always worked like a charme.
The only thing was with this design i needed to clamp it verticaly to the cabinet. And that was a rather noisy solution.. Also could have used a t coupling and a screw cap instead at the bottom. Than it could stand on the screw cap on a foam pad.
That's what i would do, skip the eastitics if its in a cabinet anyways and skip the expensive laser cutter. All you need can be found in a hardware store or pond shop if you make it from PVC. Pond shops might sell clear pvc by the metre.. Tee's, couplings and flanges etc. in standard sizes are avaiable.
In some pond shops you might find ready made solutions like these canister filters for water treatment.. They are not that expensive. I've seen people making co² reactors from it, filling it with those plastic bioballs. I would definitively do a search and a price comparance with DIY. I guess its hard to beat to diy it cheaper.
But than you need to drill a hole to connect the co² tubing.. Als not that exciting. For 6mm tube connectors look in the pneumatic industry, for example the 4/6mm x M5 hose connector with O-ring. Than drill a 4.2 mm hole tap M5 thread and screw in the connector, it sealed by the gasket on the connector.