After browsing I couldn't find a spool adapter I liked so I designed this one. It's very simple and need NO extra bits i.e. bearings, washers, or nuts. The OD is 56.5mm or 2.22in (highest measurement I could get after printing was 56.9.) the length it 75mm or 2.95in. I recommend printing with the flange touching the bed. Turn OFF supports because you can not get inside to remove them easily. I added a large fillet to the inside to help print the top with little to no stringing. Fits my Solutech Filament spools, may fit others!