Basically instead of screwing or unscrewing attachments have a double spring fixed attachment with dials on the side. So with the dial set at 0 its 3 inches, set to 10 its 9 inches.
This way you can set it at 3", strap it in then turn up the dial without unscrewing three different attachments at once.
Also please make a 1/4 inch silicon coating on the hard plastic piece that you strap the head to. So it contours to your head.
Make another head attachment so the strap "cannot" come all of the way out, inside is a circle sleeve of silicon or medical grade rubber you can put the head through, by tightning with the straps you would then not be able to pinch the head.
All of these can be after market and I would buy all three today.






