Ideally a 3D scan of the placid penis would be taken to customise the cage. I suppose just measuring length and girth might be sufficient, better than just selecting between three sizes anyway. The standardised parts of the design would be added to that. If it could have an upward extension which would both house the Dream Lover 2000 and shield the abdomen to prevent massaging of the front of the prostate so much the better. It seems a shame the accelerometer in the DL2000 cannot be used to detect masturbation and shock the wearer out of it before he can come. Ideally the cage and extension would be angled to hold the penis in the tucked position to give a smooth front to the trousers or more importantly to cross dressers, to the front of their dress. This would also make playing with the testicles almost impossible. Not sure how to handle sitting down though, don't want to crush the testes and sitting on the edge of a seat is not very comfortable. One brand of CB actually encloses the scrotum to stop access for playing, but has to be made in two parts to get them inside. That might help protect them whilst sitting. On the other hand, should a sissy maid like me be allowed to sit comfortably?
It was inevitable that chastity devices would be soon 3D printed -- and partly this is due to the lack of desire to improve their product over at A.L.Enterprises, makers of the CB-x000 devices. Their devices have always had a very annoying flaw: a seam down the middle (either sides or top and bottom) that is "sonic welded" -- but inevitably breaks. It usually breaks and catches and painfully pinches flesh inside the seam. I've lost count of the number of these I've split. Standard plastic molding processes require the seam, but more expensive processes could have avoided it. When 3D printing came about, I thought immediately: If AL doesn't offer their own seamless model (either molded or 3D printed), that will just hasten the arrival of other products that don't have seams.
Just an update: I took up the challenge myself and have started a custom cage design optimized for use with the DL2k. It will be a design which can be customized, where the main cage will be 3D printable in various types of plastic, and the custom electrodes printed in stainless steel (316L) or Titanium (or other metals). I have also designed in a PA-piercing attachment, which is electrically connected to the within-cage DL2k electrode. It is a secure design with a miniature metal lock for both the PA piercing as well as the attachment to the DL2k. Of course I will design improvement ideas based on several years of practical experience with the DL2k. I do expect to go through a couple of prototype runs, and after I have verified the design accordingly in practice, I will share my experience on this blog, probably in a couple of months from now. It is really very exciting!