The sump function is to remove the tank's water without a pump or puncture the tank, this allows that water jump the glass height. This way you only need a pump to return the water to the tank
The sump works by pressure, to prime, empty indoor air through the top hole. This is a operations scheme.
I have made the sump design using CATIA V5, for that I have generated the 3D model with press fit joints, ff which I have extracted the 2D files for laser cutting machine.
I used 4mm acrylic sheets for what I needed this configuration on the laser cutter:
To create the sump I used two sheets of acrylic, because the size of the laser cutter would not let me do it on a single sheet. In the end, although I've done a press fit assembly, I had to use silicone to make sure that the joints are fully waterproof.