this is a simple cat-door design for indoors for larger cats. the hole has a width of 45cm and 25cm high. it is meant for a 4cm thick door. the rims are 2.5cm thick from the front, and 1cm thick from the door.

so in total 50cm width, 27.5cm height and 6cm thick (including the part that is 4cm through the door cutout)

for it to fit on your printer there are also half parts of the gate. when printing don't just print 2 of this version print one after inverting it with ctrl+m followed up with Y (in blender) remember to export in a .stl file. this way you have a left and a right part.
if you use the version of the whole model, the sides are not 100% even, don't know how that happened. and the smaller holes for the screws are only 4.5mm which is not large enough for the screws I'm using.

to screw the 2 pieces together use 4 patentbouten (dutch). patent bolts? the back part have smaller holes of 4.5mm. the front part have smaller holes of 6mm. and the larger for the screw head is 8 mm in diameter.

when printed in multiple parts: for adhesion of the split parts of the front/back parts using superglue is a strong bond and the most seamless finish.

for printing remember that the front part has overhang so the front part needs supports.