I love watching people work hard. Well done, it looks good.

I will be  watching cheers

Making the frame more suitable for the job will prevent those warping issues far more than any number of coats of paint will do.

Useful video. I would not recommend coating the wood with PVA prior to applying the primer as this will cause the primer not to adhere! If you use primer, then you don't need to apply PVA. An alternative is to use Cuprinol Garden Shades green. You'll need 3 coats, but it is easy to apply and dries quickly!   You can apply Curprinol shades to the bare wood and keep the primer for something else.  Thanks for uploading.

What thickness and type of board did you use.

Thanks, really interesting. I also have a problem of "This table should not be occupied by this" 😂
Question: What are you doing with tracks? Layout is going to be assembled and disassembled each time?

Tt= tiny trains

Nice baseboard! Do you happen to have a link of where you got your hinges from? I can’t find them anyway. Do these hinges they have a specific name?