Can this part be custom machined & what's the cost?
This is a frequently asked question, sometimes by email with blueprints & full specs but often not too specific. The short answer is that almost any part can be custom machined if your budget is large enough.
The full answer is longer ...
Generally speaking if a part is available from the manufacturer of the light that's the place to first look. Manufacturers buy in volume & receive quantity discounts that are often significant. Machining is done on computer controlled (CNC) machining centers that never get tired & don't need a bathroom break or lunch hour. Optimal set ups have been developed, tooling is job specific, parts run fast & their price is as low as can be found.
If the factory doesn't make a part there's often someone on CPF that offers parts & accessories. A look through Custom Buy/Sell/Trade or a search on The Marketplace shows hundreds of items to fit almost every light. Costs are pretty low because most items are still made on CNC equipment. Solid value for the money spent.
If there's nothing available in the market any part can be custom made - at some price point. FWIW I look first for off the shelf parts before firing up the lathe or mill. One example is the aluminum throttle body spacer shown here:
Doesn't get any easier to make than that ... so why did I spend $79 USD instead of making one? Let's cost this out:
Aluminum plate @ $5
Drill & chamfer 4 holes @ $15
Drill & bore central hole @ $25
Band saw plate to rough shape @ $15
Grind, blend, polish plate @ $20
Purchase 2 gaskets @ $10
Purchase 4 bolts @ $8
Total cost = $98
This doesn't factor in the cost of shop lighting, heating or air conditioning, tooling cost, liability insurance, trips to the hardware store, etc. Add another $20 USD for that & the custom made part costs 150% more.
Parts are parts, whether they go on an automobile or a flashlight. Rule of thumb is that a custom part will cost at least twice as much as the next lower priced option. Depending on complexity it could be 3X or 4X more.
In addition to cost there's one other roadblock to clear - can you or will you supply the print? No need to be fancy but any machine shop needs a top/front/side view with dimensions. Simple parts can be hand drawn on a sheet of printer paper, more complex items need a clear 2D print.
Hopefully that provides some insight into why custom machined parts cost what they do.