the top and bottom parts are printed separately and snap together at the hinges. this can take a bit of force, so I would recommend doing this before inserting the blade.
I would also HIGHLY recommend printing the blade inserting tool. It makes it much safer to insert the utility blade so you don't cut yourself.
The top piece can be printed without supports if your printer is well tuned (even if orca complains about a floating cantilever), but adding supports shouldn't cause any issues.
I printed using Elegoo Clear PLA at .2mm, no supports, small outside brim for the blade tool.
The author marked this model as their own original creation.