helping hands ball attachment

I have some cheap helping hands from Aliexpress. but they came with double adaptor ball joints, I wanted to have individual helping hands. So I replicated some. The insert is to give it a little more strength, because you print the piece standing up for the screw threads. but this makes it a little weak along the layer lines. I just force the insert in, its such a tight fit, I don't think glue is necessary. You might even just print the ball joint thing without the insert and it might be fine, your choice! Its a pretty tight fit for my helping hands which I think are these:

I put the attachment into a wood vice and then I was able to push the hand onto it. but it takes a fair amount of force. but if I made it any looser, it would not hold its position. I found this thing, which can be used (convert to a hole in tinkercad) to produce the female screw threads for the helping hands too.