Menger frame fractal
thingiverse
Variation on a Menger sponge. This may work with very good bridging - otherwise use the base option and a thick frame. The fine detail stl might work on a resin printer.
Download Model from thingiverse
With this file you will be able to print Menger frame fractal with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Menger frame fractal.