I don't think I have anything that's worthy of the "pinnacle" award, so I'll go with most niche & prized: a hand powered tubular key cutter, the HPC Pocket Cut-up.

It's a mini (roughly measuring tape sized) hand powered all-in-one cutter+jig that can cut tubular key blanks to any code. Any professional would probably get an electric machine instead, so I'm not really sure who needs the pocket version. The small size makes sense for someone who doesn't cut keys for a living, but the price is ~$300 usd. I found it useful for replicating the service key to my apartment laundry machine, which gives access to the hidden start cycle button which normally only presses when you pay via the coin slide. The hand cutter has standard cut depths already set so all you need to do is pick the lock with a cheap impressioning tool and measure the tool once the lock opens to retrieve the key code, which is easily translated from caliper measurements to key code via publicly available lookup tables.

At ~$300 I may have saved some money over just paying since our laundry is $5 per load and I've used the replicated key for over 5 years (back of napkin math says as long as I've done laundry more than once a month I saved money, not a high bar to clear). I could have done it much cheaper by ordering custom keys online, but being able to cut a different code in 10 minutes if I got the measurements wrong proved to be really useful.