If you want the lid to stay open in an angle, you need 1 or 2 M3-10mm screw, or the new plug inserted into the hinge.
Screw
or
The support material is easy to remove, if you are a little careful.
You will probably need to use a little glue to attach the part of the lid that fits the toolbox. (If you only glue the front or the lid, you will still be able to replace the inlay / inserts)
The design process:
Designed by me in Fusion 360 and Vector Magic Desktop
I'm just a hobbyist, trying to make some things, not a professional designer