Today I started on the chassis. I’m going with aluminum, and trying my hand at welding it together. I’ve been practicing aluminum TIG for a few days now, but still just getting the hang of it. I could really use tips, especially on making fillet welds.
Here’s a rough CAD model, mostly used to figure out what the box tube frame should look like. The grey sketch lines are where my legs should go, so I probably won’t be using the steering wheel shown in the CAD.
preliminary CAD model
machining the two main struts together to keep everything aligned
cutting channels to fit the cross struts
frame components ready to weld. It was cool that it only took two clamps to hold everything.
close up of the rear cross strut joint
top and bottom are welded. Held vertical to weld a reinforcement block in the "arms"
close up of the support block in the "arm". The end of this will soon have a C-bracket that will hold the pivot for steering the front wheels.
top view of progress for today
dramatic front view
more to come tomorrow.
Amy Qian 
wondurfull information thanks