Bases for SPARCO Seats. Who can make'm?

Well I’ve been looking arounf for bases for my SPARCO Torinno seats. I have the sliders, just no bases yet. One calgary shop told me SPARCO has like a month backorder on bases right now. Who knows if that’s correct or not, but anyhow, looking at the bases, it’s really only 4 pieces of metal with a lap weld on the 4 corners. I know back on the east coast a few guys made thier own but only used bolts to tie them together. I want to make sure this is structurally sound, so I’m not going to ghetto it, but it’s so simple that I’m sure these can be made easily, and for cheaper than the $150 per side that SPARCO wants for them.

Any input?

My racing seat is bottom mount, so I took the stock rails, cut off the part that attaches to the stock seat, bought a 90 degree metal thing, and bolted that to the rail, then bolted the racing seat to the top of that. Pretty sturdy, but it wouldnt hurt to weld it I guess.