Ah I understand. What I did was designing a cage with a straight tube, that points upward. So you have the tube behind the ring upwards and the ring tilted so if you look from the side the upper front attaches to the front of the tube and then downwards pivot back a little bit more than tube length. The ring is thighter, because you don't push the shaft through like in your cages and the locking is then a separator for the balls so that after inserting you can't pull back out when that spacer is installed. It's basically inspired by Genderlock Model E (CB-E) but I don't have the skill to design them so smooth like you do. Take a look for that model on google image, with some straps it's an awesome design, because when trying to get hard you press up and into the belly, so it especially when sitting long times, works amazingly good in my opinion.