6061 Aluminum Tubing (or a KTM subframe)

[Tekime]

Where on god's green earth can I find 3/4"x5/8" 1/8" thick 6061 aluminum square tubing? Tried McMaster, Grainger, metalsdepot, eBay....

Metrically speaking it's 15x20mm, 3mm thickness

OR if somebody has a decent '06 KTM 250 subframe for cheap, or any broken KTM subframe I can hack up. Just patching a small piece on my subframe

[Tekime]

Well, fun facts: as far as I can tell they don't actually make extruded aluminum tube in this dimension due to tolerances. Not a single source out there.

Looks like I'll be getting some 1x1 square tube, cutting it down, and getting it welded along with the patch (unless a wrecked subframe comes my way first)