E3Dv6 Shroud and 40 mm Duct Magnetic Coupler Remix

Remix of E3Dv6 Shroud and 40 mm Duct w/ Magnetic Coupler for 6x3mm Magnets

Well maybe a rethink rather than a remix.

After some tightness and adjusting the sizes of the original files I soon discovered that you needed the holes to be tight but not too tight for the magnets and after a few iteration and glues I thought I had it and one magnet pulled out... so decided to rethink the idea and make it "user friendly".

Magnets slot in from the rear now and I just used a little hot glue to ma