Immersion Duo 5800 tripod mount

Redrawn from original concept by [ARGHtur](http://www.thingiverse.com/ARGHtur/about).
[DUO5800 tripod mount](http://www.thingiverse.com/thing:959906)

V1 -Added slots for Velcro strap and changed shape for printing standing upright

V2 - increased slot with to 26mm for 1 inch Velcro strap. Added hole for tripod mount spring pin

V3 - Changed 1/4 inch nut to 1/4 inch pressed insert with 8.5mm od