There don't appear to be any threads on this subject, so I thought I'd share my latest attempt to make use of my usual bumper crop of jalapeno peppers. This was my first attempt, and my results tell me it's a no-brainer. I'll keep this simple enough even I can follow it.
Chipotle "chili" powder can be made with any reasonably hot pepper. Jalapeno is traditional, but pablano, Serrano, probably even hot wax peppers will work. The thing that makes it chipotle is the smoke.
Note of caution: I thought I was going to be cool and use a barrier skin cream to protect my hands. Conclusion: wear gloves!
The first thing, of course, is to pick and wash your peppers. With jalapenos, it doesn't seem to matter if they are green, orange or red, as long as they are no overly ripe, or rotting (duh!). A little weather checking doesn't hurt anything.

Next step is to remove the stem ends and split them lengthwise. I removed the seeds and membrane to reduce (I thought) the heat, and make the powder more versatile. If you don't clean them out, I would suggest reducing any recipe calling for the powder to 1/4 what's called for!
I loaded the cleaned peppers onto the racks in my portable smoker. I won't go into the whole "how to smoke" dissertation...I'm assuming anyone attempting this has smoked other stuff before. But this is going to be a looong smoke, so I'll suggest using smoking pellets. The "sawdust" sold for use in small smokers is meant to be used dry, and might last 45 minutes per pan, if you're lucky. Smoking pellets are made like pellet stove pellets, highly compressed. I used Lil' Devil pellets because I have about 200 pounds left over from when I was a distributor, but feel free to use Traeger, or any other hardwood pellet made for smoking. Here's the racks, ready for business.

To get the desired result, you need to smoke the peppers somewhere between 12 and 20 hours. I got good results with only two loads of pellets. The first tray lasted about 4 1/2 hours, and I reloaded it about midnight. By 9:00 am the next morning, the peppers were thoroughly smoked.

Now you have your smoke flavor, but it's doubtful the peppers are dry enough to grind. Any that are the least bit pliable need to be dried further. You can put them on racks in a 150 degree oven (not on a cookie sheet) and leave them over night. I used my dehydrator, set on 150 degrees, and it took another 12 hours to turn them crisp.
Then it was just a matter of grinding them into powder. Unless you don't breathe very often, or can hold your breath a really, really long time, I'd suggest wearing a dust mask, as a minimum. You're dealing with pepper spray in powder form! The air borne capsicum will clear out sinuses you didn't know you had.
Presto! The resulting chipotle power ready for spicing up any dish you want.

Yeah...that 3 pounds of peppers yielded 4.8 oz of powder. Since 1/4 to 1 teaspoon goes in each recipe, this will last me through the winter, for sure.