My 1st DIY build

[EddyCurrent]

A few things pop out for a start.

1. The gantry is not deep enough, it would be better to have two cross pieces and put the ball screw between them. The reason is that the further apart you can put the rails the better, it helps reduce twisting.
2. Are the X ball screws that low down for a reason ? it's regarded as advantageous to have them level with the rails, it looks like you could raise them okay.
3. Most people use 20mm aluminium plate for most of the components.

This is a good diagram to study.

Do it yourself CNC router: Design Considerations, the Gantry

Edit: Dean, I was faffing about with an edit while you posted.