Silly to buy prefabbed LPB's when you're using them in quantity, want special/legended lenses, etc.
Instead, tactile switch, indicator/LED and lens thrown together and held in their respective places, mechanically, by the rest of the assembly (e.g., as is common on much consumer kit).
Conceptually, a lens that acts as actuator and can be held captive (e.g., front bezel) with a button and indicator hiding behind it. Actuating force transfers through the (rigid) lens to the button. Light from the indicator makes the return trip through the transparent/translucent lens.
Ignoring shape of lens...
What arguments re: placement of indicator and (low profile, low travel, "tactile") switch:
X | Y |||||| Z |
(assume '|' denote body of lens/actuator)
Switch at X (and/or Z), indicator at Y provides direct path for light out through the lens. If lens (as actuator) is constrained so only allowed motion is along axis, then it can equally actuate switch at X (and/or Z).
[If actuator is sloppily constrained, then there is a risk that it can tip and bottom out on the indicator/PCB without reliably engaging the switch]Indicator at X (and/or Z), switch at Y ensures switch is more reliably driven by actuator regardless of slop in mounting. But, light from indicator(s) may be partially blocked by the alignment (lack thereof) with the lens itself.
[Of course, relative placement and scales can play a big role]Also, risk of mechanical shock transfered to indicator and/or switch
[There are obvious ways to minimize this]From disassembling kit, it seems like a common approach is to use a web to support the actuator/lens -- shooting the web as part of the same injection-molded actuator/lens assembly. (I'm trying to avoid as many molded parts as possible). And, a translucent lens material allows more leeway in positioning the indicator without a noticeable "hot spot" in the "display".