This is not meant to a sales pitch, just information. If you are wanting to build a basic crossbow but lack the machine tools to make your own trigger this may be a good option for you. It is a basic roller nut and trigger, no safety, and works well on bows up to 150 lb. Maybe much higher but it has only been tested to 150. It uses a Delrin nut with steel striker plate and a steel trigger.
This is the first one but more will be available if there is demand.