Dick Passthrough

It can be difficult to get one into another for first time. But don't worry! Have a little patient and you'll make it. After that you'll be able to put one into another easily. 

If It gets stuck - twist it more and it'll be fine.

Also I made a version with bigger gap between parts in case if you'll fail with original one.

I recommend to make it 0.12-0.16 layer.

Good luck!