Hi there,
This is Bogdan from Romania.
I'm a mechanical engineer - specialized in the industrial robotic field, 3D designer and modeler (from time to time and some projects I could make the functional prototype too).
I'm doing product design, industrial design, reverse engineering, ideation, etc.
I have over 15 years experience working on various systems/devices across multiple industries, from concept to launch.
1 - I will need to see your sketches/ideas/drawings
2 - if your design requires drilling the body of the gun (in any way) you should get rid of the idea (i confronted this situation when designing a modification of the upper receiver for a AR15 rifle)
3 - what do you mean by "modular trigger lock)?
4 - there are two stages of the process - design for prototyping and for manufacturing - I will recommend you to chose to prototype. most often, when the client has the first functional prototype in their hands, come up with new ideas, requirements for improvement, changes, etc...
For any more questions we could chat here.
Regards
Bogdan