Design Repositories
Makerbot/Stratasys’ Thingiverse
Makercase – A quick way to create basic box designs for the laser.
Obrary – an open source library of designs that you can download and customize. Features several projects specifically for the laser.
Lithophane Generator – Make a 3D printable lithophane out of any photo!
All3DP’s Index of 3D Design Repositories – This is an unvetted list, I can’t vouch for any that I haven’t specifically listed above.