Is there a way to join two printed projects?

[mechadense]

The best solution is an interlocking structure (dovetail joint). ABS should be gluable with acetone (I havent tried it). If the contact area is small and has long contact edges you can plastic weld the parts together by using a thin pre-extruded plastic thread an an old or covered temperature regulatable soldering iron. Also there is the possibility of using short pieces of filament as dowels. Heated nails in preprinted slightly to small holes can work too. If you glue make sure there is no lever effect possible.

[MysteryAlabaster]

The best solution is an interlocking structure (dovetail joint).

I've used this for a few things that I had to print in pieces. It usually works well, but sometimes you have to adjust the size of the clips, because even though they fit together in the modeling program of your choice, they might not fit so well when printed. Usually they're too tight, I have yet to have clips be loose.

[Slatye]

I've used this for a few things that I had to print in pieces. It usually works well, but sometimes you have to adjust the size of the clips, because even though they fit together in the modeling program of your choice, they might not fit so well when printed. Usually they're too tight, I have yet to have clips be loose.

That's pretty normal for 3D printers; the output part is always a tiny bit over-size. On the Stratasys one at uni we make any tight-fitting parts 0.1mm smaller than they should be and that generally results in a nice fit.

On the other hand, for laser cut parts we aim for a fraction oversize (ie make a tab 5.05mm to fit into a 5mm hole) since the laser cutter always makes things very slightly undersize.