One thing is clear after the first protype failed half way. No more manual cutting of parts. So I redesigned the model of the prototype again such that almost all of it can be cut using a single 4x8 sheet of sheet material ( MDF in my case). I outsourced the job of CNC cutting to a vendor and had the new parts to assemble within a day.
It took another one day to bang together all the parts in place for my next prototpe.
There was a night and day difference between this and my first prototype. The frame was really solid for its intended purpose and the gantries rolled smoothly over, the rails.