How to remove seeds from thin and thick walled peppers
You will need a sharp knife and cutting surface. A grapefruit spoon is helpful for larger peppers. The spoon tip can be used to both grab and cut. Gloves are also recommended and so is good ventilation. Caution when washing up in hot or even cold water, Capsaicin fumes will saturate the air near the cleaning area and it will become like pepper spray. Caution with the sharp knife, don’t rush.
This is how I remove my seed from a thin walled pepper like the below aji amarillo.
Slice the top of the pod and slit the pepper end to end. Pull the pod in half then scoop out the seeds with grapefruit spoon or back of knife. You can use just a knife for small annum peppers like pequin.
With most peppers, after you remove all the seeds from the pod, you need to clean it by removing the non seed (placental) plant material. Save this stuff as this is where capsicum concentrates.
For thick walled peppers like rocoto you need to cap the pod by cutting around the top at an inward angle.
You can either remove the seed from the cap if you are cooking with the cap, or just dry with seeds attached to cap. After a few days remove the seeds. Dry cap is very hot!
Transfer the seeds to a sheet of white printer paper and allow to air dry for 48 to 72 hours. Write seed batch information on the drying paper and photograph. Continue to remove non seed plant material as seeds dry. Aluminum foil also works well.
When seeds are dry and ready to store, transfer to paper envelopes and write seed data on envelope. Store with silica gel desiccant in cool temp and low UV environment.
If you harvest a large number of peppers at once for seed, dry your pods after you seed them or just cook a big batch of Rocoto Relleno. The pod cap and placental material it is high in Capsaicin so use it.