tetrahedron
thingiverse
This is a tetrahedron (3 sided pyramid (but not) if you like). Simply upside down! yes you can flip it the other way if you must :)
Download Model from thingiverse
With this file you will be able to print tetrahedron 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 tetrahedron .