1rst build, time to do next step

[JAZZCNC]

Presuming this is all ALU plate.?

Quite a bit of unnecessary weight on there.?
Don't need inner and outer gantry sides or spacers between them. They add very little extra strength only excess flab
Don't need the all the Motor plates etc sitting on gantry side and could just mount motor on inside above screw and thru gantry side if single gantry side.
Don't need the piece that Y axis ballscrew fastens too with small change of design.

The cross piece that rails sit on still looks like single piece of Alu with no bracing.? This is the major weak area which will flex under cutting conditions.
I've built a gantry using plate like what you seem to be wanting which is very very strong. With just a few changes it's half the weight and much stronger and lot neater. It protects the ballscrew and motor by completely encasing it. See pics of it part built and Cad model.
Actual Design was modified to Cad model and ballscrew raised and Motor brought inside gantry connected to screw with timing belt.
Pics of actual machined parts are only for visual purposes.!! IE ballscrew sat on offcuts to show rough position with quite a few pieces like bearing plates and strengthening braces missing.

There's also braces inside the Gantry which are not shown in Cad or pics. The Z axis motor mount is also different and doesn't use upstand pieces shown in Cad instead using a solid 2 piece machined spacer part which covers belt/pulley.

Hope this helps.!