Oculus Rift DK2 IPD adjuster +4mm
I've recently designed this IPD adjuster for Oculus Rift DK2 - it widens the iPD by about 4mm (+2mm per lens) bumping it up from the default 63.5mm to 67.5mm.
Like other non invasive devices of this type it uses B lenses and makes them about 1 mm higher than the A lenses (the adapter has to be 4mm high due to DK2 lens clip design) which can bring them slightly out of focus but should be fine for most people.
I didn't have time to thoroughly test them but at a first glance they seem to work like expected.
[EDIT]
Added 3mm thick version of the adapter - requires hardware mod, see instructions for info.
[EDIT 2]
Uploaded version 2 of the adapters - they should be more resistant to under and over extrusion (v1 could be a little loose if printed with slight under-extrusion). Also they Should fit the DK2 tighter leaving less possibilities for misalignment.
[EDIT 3]
I've made parametric version of this design. You can find it here:
http://www.thingiverse.com/thing:543445