What we want is a Star Trek-style replicator. What we have are a bunch of different machines that can spew out various 2D and 3D shapes. For the foreseeable future, you’ll still need to post-process most of what you build in some way. [Stuff Made Here] had a challenge. He often uses his plasma cutter to create complex sheet metal items. But the cutter is two dimensional so the piece doesn’t look right until you bend it at just the right places. If you are doing a simple box, it is easy to figure out, but getting just the right spot on a complex bend can be a challenge. His answer? Attach a marker to the gantry so the machine can draw the lines right on the sheet metal.
Sounds easy and if you were willing to do a pen pass separately and then remove the pen and do the plasma cutting it would be relatively easy. However, that seems kind of crude. Mounting it permanently requires a way to raise it up when cutting — and it needs to survive the noisy environment near the torch. The pen would also dry out if you left in uncapped. The answer was using a permanent marker with a click retractor and let the mechanism extend and retract the pen point on command.
The torch uses an air system to raise and lower the torch. The mechanism for the pen uses two valve and two springs to allow the pen to go up and down appropriately. There don’t seem to be any exact plans, but your cutter will be different, anyway, and anyone who is using a plasma cutter ought to be able to figure it out from the explanation on the video.
The results look good and it is surprisingly useful to have marks drawn on the flat pieces, especially for bend lines. If you are lacking the cutter, we’ve seen many builds in the past. You might also get some ideas from pen plotter builds, just remember the unfriendly electrical environment around the torch.