Need help in chhastity making

I'm trying to make a chastity device. Now for this I'm planning to use a
1. 45 degree elbow piece
2. Metal/Plastic ring
3. Lock
4.elbow piece cap
5.glue
First I will shut the one end of elbow piece with a cap with the help of glue and make a small hole half the size of diameter for peeing purpose then on the other side just at the beginning surface make a small hole enough to get a lock inside, then after inserting my balls and cock through the ring and inserting the cock through the piece I will lock the piece with the ring.
I hope I'm being clear here.

Now I found a plastic ring in my house its of 1.5" diameter and I thought of trying it on my balls and cock. after inserting my balls and cockI feel quite a tightening and a dull pain around my balls specially around the underside of scrotum, and sometimes on the whole part whenever my cock tries to get hard. Is this pain normal or do I change the ring?

Is there any better way to make a chastity device?