3D printing source material and superglue
CA glue works on PLA, especially if you're gluing parts that fit together rather than small surfaces that just touch, but I'd encourage you to consider alternatives just because there are so many more ways to attach things when you have freedom to design the parts, and non-glue approaches admit disassembly, repair, etc.
Some possibilities include:

snap fits
parts sliding into grooves
threaded holes and bolts
threaded interfaces.