Just thought I'd check in here. All the Hardox parts have now arrived, along with some cobalt drill bits and cutting paste for cleaning up the holes. Anyway, I've been working on cutting the HDPE. Progress is slow but steady, and these bits are a lot neater than the first test piece. I've got about 30-40% of the chassis done so far, and I think I have all the fixings I'll need. You were right about the block plane, Overkill, that does leave a nice finish. I've also bought a 35mm Forstner drill bit, to hopefully drill out some nice, clean holes for my motor mounts (which will be made out of parts of the chassis). However, I've found a decent way to make holes in the outer parts of the chassis, where the 'nose' of the motor gearbox has a resistance fit. That should hopefully stop them rotating even if the motor mounts do become loose on the inside. Plus, I can screw the old metal plates from the drills onto the other side to keep the motor in. Because I'm terrible at explaining things, just have a look at the image below. I've tried my best to take the linac apart again, and I just can't separate the main barrel, or even the outer tube from the base. I think I'd have to grind or hacksaw it off if I really wanted to. But I think given your advice, Overkill, I'm gonna try and just screw the slightly modified base onto my mounting bracket, and take it from there. But anyway, getting the main chassis and locomotion running first, still got to alter the wheels so that they sit nicely on the motor axles. More updates soon!