Conducting Power on a Scratch Built Chassis

After my provisional Henry that was built around Spencer's chassis and had to replace him, I felt intrigued by the idea to build scratch built frames for custom engines/powered stock that would use the "Thomas type" drive unit. Seeing as official engines with it have a conductive metal strip to finish the circuit, I thought there might be some way to achieve the same method without cutting up an existing chassis (which I can't do since I only have four remaining "Thomas type" engines). What's the likelyhood of getting a custom one to run by duplicating the metal strip with aluminium foil or similar? The motor terminal that goes under the piece holding it down would still touch the strip like the originals, though I have yet to understand how the contact right under the switch doesn't have to be connected. I'm asking because unlike the C Tender and Flat type, the "Thomas type" doesn't use wires for the motor or terminals. At least theoretically, it should be easier to get one of these to work in a scratch built chassis than the ones that need soldering. I'd love to build such versions that don't have to replace any of my existing fleet and could easily have everything swapped out when need. If there's a way to get it to work with the foil, I'll gladly attempt one and see what happens.