Ive been filling gel caps for years, at least ten, maybe more. And they're still my go to edible, especially at night. My wife and I have made rso/feco caps, sift hash caps, rosin caps, but most often simple weed caps.
For weed capsules we decarb the buds first, for 60 capsules I use 15 grams of buds, but we sometimes use popcorn buds from a variety of plants. Just remember junk in junk out, or in this case trim capsules won't be like bud capsules for strength. After decarbing (we use a nova fx) I grind the buds into flower. Then I use a 1 cup measuring cup to hold the ground up weed. Ive been using liquid lecithin for these because it's simpler than using the powdered. I use 'now' brand for what it's worth.
Then we fill to the 2 oz line on the glass measuring cup with liquid coconut oil. I stir the weed oil slurry until its mixed well. This will making 60 size 00 capsules give or take a couple. You can scale up or down from there. Because the mix becomes a thick slurry it's hard to fill capsules. So I cut off the tip of a pipette to make it easier to fill capsules. I just fill and cap each one by hand.
That's it your basic weed capsule. If desired, you can mix varieties, add cbd, or another cannabinoid isolate. To figure potency, first have a good idea of how strong the weed is and divide the total number by the portions, in this case 60.
Ive found you can really notice the varietal differences in weed caps, more so than a rso type edible, but rso capsules can be easier to work with and fill, and you need less. I like capsules 35-50 mg, stronger than that it gets hard to fill enough weed into capsules. It's obviously easier to make strong capsules with concentrates, just be sure to decarb unless your interested in thca or cbda edibles. I've also started adding terpenes, at the rate of 5 drops per 2 oz of the slurry mix. The sativa mix terpene I used seemed to make a difference on caps filled with columbian gold popcorn buds I recently made.
For sleep inducing caps we start with a few grams extra of herb and decarb half the weed twice, and half once. The extra decarb degrades the thc making cbn, and then cbn's help with sleep. Keep in mind cbn's are not all that psychoactive, that's why I add a few more grams to the mix. Capsules filled with abv can also be helpful for sleep.
There you have it, if you want to make simple consistent edibles filling gel caps is a great way to go. You need weed, or concentrates, gel caps, we use size 00 empty gel caps, plastic pipettes, liquid lecithin, and coconut oil. Everything except the weed you can get off amazon.