A printable solution for mounting two 3.5" hard drives in your Jonsbo D31 computer case, while still allowing for a 120mm fan to be mounted at the front. Note that this requires you to be running a 140mm long power supply in the top-most position.
Clearance notes:
8 hard drive screws (#6-32 UNC) to screw your hard drives into the mount
4 additional hard drive screws (#6-32 UNC) to screw your mount into the case
4 M4 or #6 washers
Print out the caddy, then fold the edges over until they're 90 degrees (the inside of those V shaped grooves should touch each other).
Make sure to install your front 120mm fan first, as it's difficult to do so later. You may also want to add a fan filter, if desired.
Screw your hard drives into the caddy with the first of your screws, using the picture as a reference. Note that if you're looking at the top of a drive with the SATA connectors at the the bottom of your view, the adjustment holes should extend out of the left side.
Place the caddy with drives into the case, making sure to slide it as close as possible to the fan while still having the mounting holes align with the original hard drive mounting holes in the case.
Screw the remaining hard drive screws (with washers) through the bottom of the case into the caddy.
The author marked this model as their own original creation.