I was planning to make an enclosure with aluminium sheet until I saw latest prices of it locally. I do have lots of sheet steel (normal mild steel) in various thicknesses and some stainless. So I'm considering all steel construction now, but I read somewhere one is not supposed to have ferrous steel anywhere near the vacuum tube anode, the tank circuit etc and that those sections have to be shielded from steel parts with aluminium or copper. Otherwise steel will magnetically couple to the circuit and it will cause eddy current losses. I would consider stainless, but it is horrible to tap for tiny m3 screws without special carbide taps. So normal steel seems the best option for me. The eddy currents precaution seems to make sense, but at the same time I saw lots of amp pictures with steel enclosures. So what is the truth? Can I use 2mm thick (80 thou) sheet steel for the chassis floor, the front, the back and dividers? Then I planned to use thinner steel sheet (0.7mm) bent to make a top cover. What do you think?