Does it have to be identical, there used to be quite a few companies that sell extrusions of different shapes.
The extrusion made from one side is a common one, and could be joined if necessary?
Max.
In terms of size it does not have to be identical, otherwise, yes. My ideal size would be 40x40mm. I may be able to get two heatsinks along with a metal bar that could be attached at the top to join them together, but I think that would probably reduce the thermal conductivity. It would also be a hassle to build because I need several of these. Does anyone know a company?