Publishing this after a few iterations and field testing; The generic visual fault locator (which every supplier seem to re-brand) used in the fiber optic industry has a built in flaw where the selector-switch sticks out beyond the chassis resulting in technicians inadvertantly powering on the device from their pocket, draining the battery.
The amount of times I've chased my own tail searching searching through panels, enclosures etc for my infrared indicator light - only to find the battery has drained - has happened more than I can count.
The shroud has a slip on fit - and locks in with rounded tabs at the business end of the VFL. The area around the switch has been extruded a reasonable amount to where I no longer have the above mentioned issue. It also tapers off to where the connector lid does not pop off as easily.
There are two versions, one with slots for magnets (10mm x 3mm) - and one without. I print these with PETG at a relatively high temp (260C/80C) 0.16 layer height - and max walls. I'm sure this would work well with TPU as well, but might have to modify the relief slots - or just close the gap in the slicer.
I've printed these for all 7 of my technicians - and have not yet had any breaks or failures, although they are subject to relatively careless handling and storage...