Bolt+Screw
thingiverse
There you have a M20 nut and screw with a conical top. I put the STEP files fi you want to change the size.
Download Model from thingiverse
With this file you will be able to print Bolt+Screw 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 Bolt+Screw.