I have mold and some spare parts to build a Shippen Helmet. Could be built as air hat or with regulator. More pictures of helmet are on my page. Used this hat in GOM for 10 years before I went into offshore boat business(next 20 years). Bilt this hat in 1966 when I was tending for George Swindell (Swindell Helmet). Helmet is neutrally buoyant(1/8" sheet lead is sandwiched in fiberglass). Use spear gun rubber jock strap(light tension) to stabilize helmet. Uses Desco exhaust. Uses sewer pipe "O" ring in neck dam that stretches over ridge in helmet(never came off-foolproof). My hat has copper tubing at base but mold has built-in ridge at bottom of helmet. Back then, three of my friends built helmets and one made the current mold that I have available. Will give advice on building. If anyone is interested let me know. 870-447-2603
I used a KM adjustable regulator on the helmet, but took it off and preferred the US Divers regulator. With the exhaust positioned where it is it was an easy breather. Had to stretch the spring in the regulator so it would not free flow on deck when we were diving air at 200' and air was set at 185 psi. Also have mini bail out bottle available. Back then none of the divers used bail out bottles even at 200'.
You will love it