This is a hollow ball joint meant originally to replicate a helping hands coolant tube. The staying power isn't quite there for it to be used as a helping hand arm (at least without some internal wire helping) but the joint can be used for other things I think. If you want a loose joint that you can assemble by hand (pops right in) I suggest the loose tolerance version. Other versions need a little help either from a mallet or a heat-gun to get the joint in initially. If you don't have a heat gun, you could probably use your printers heat-bed to warm the socket/base of the joint and then quickly insert the ball/head of the joining piece before the base cools.