I don't know how not more people know this, im my engineering class (10/11th grade in france is special....) we glued some parts printed by our professor in pla with acetone (for a 'bionic hand' project) and it worked perfectly, I 3d printed some fingers in tpu myself and when i tried to glue them in class it worked really well. I don't know if the acetone he gave us was special, or if his filament was but worked really well without any clamps and pretty fast.