Aim: Private use for the P900 I have access to.

I used a lathe to cut a standard 67-77mm step -up ring such that the inner part had 69mm outer diameter. Then used this thing to elongate the step-up ring along the lens axis. Glue the part onto it.

Why: a) The P900 pulls in the front of the lens such that a standard step-up ring will jam it (imminent breakage!) b) I use 77mm filters, all over the place, even on lenses with 52mm filter thread (this is the most "extreme" case; less than 9mm "stick out")