Go to your local hardware and buy a blister pack of 1” black plastic chair leg protectors…the kind that go on those cheap tubing / stacking chairs. They cost about a dollar for a pack of four in Canadian Tire.
They fit perfectly snug over the switch end of a 501 - they won’t fall off, and your light will NEVER come on accidentally. Pop it off when you use the light, and pop it back on again when you’re done. The other advantage is that your 501 will tail stand like a champ. Of course you have to take off that silly piece of string they call a lanyard, but that’s the first thing I throw away in any event.
I suppose if you needed the ‘lanyard’ you could drill a 1/8 hole in the corner of the plastic doohickey and run the lanyard through it.
I don’t really have that problem, but it’s still a Good Idea!
If I may, I EDC a 501b in my “work pants” (redundant, because I never wear pants except for work, but I digress) front pocket. I got Very Tired of hitting it with the front of my hand while walking!
SWMBO (she, the Sage of the Shrine of Singer) graciously agreed to make me a “torch pocket” inside my pants pocket. If you’ll stand your torch in the bottom corner of the pocket & lean it against the front, pinch the pocket material around the light and stitch it where you can reach. It doesn’t need to be tight, and if you’ll leave a little non-stitched bit at the bottom, you can still use the pocket more-or-less normally!
I know most people do it, but I’ve never carried a light in my pants pocket! It’s always been a 2-AAA penlight in a shirt pocket (a Preon 2 for the past couple of years) and one or two 1-18650s in my jacket pockets.
The 501s are always a good choice, and lately I’m fond of the EDC from I-O and the S3 & S2 units from Fasttech. Lots of light for a long time in a small unit, with redundancy.