Another brainstorm, perhaps slow, but cheap.
Dip a thermally conductive rod into molten beeswax allow the wax to solidify
and then heat the rod and slide the tube off. Copper wire comes to mind, you
might have to pull it through what jewellers call a draw plate to get it
straight enough or put some serious pull on a length.
To make rods you would fill a copper tube.
Look into the mold release compounds the candle makers use.
I saw all kinds of brass rod and tubes at a hobby supply for modelmakers.
Brass has reasonable conductivity.