How about instead of screwing with the Eff of the materials with the CT, just have the CT affect the number of runs you can use the CT,
what the heck, is the CT a mold? is the blueprint information store magnetically? It makes little to no sense that it would degrade with use. What kind of RP lore is behind a blueprint becoming hard to read translating into having to use more units of wood to build the same house because the blueprints are an old copy instead of fresh out of the printer?
Now if you want to say that the earth corps have various licensing restrictions in place that limit CT production runs because of a syndicate contractual agreement.. That makes allot more sense, we don't need to put everything on a curve. Basically if you dont need to come back to me for something i can't charge you for it it makes perfect sense if this is X number of units of Items per CT or X number of production runs before its license expires and you have to go get a new one.
Fact of the matter is that the diminished return mechanic is stupid in some cases its used in to justify the time based skill progression. If prototyping was the same as im suggesting it would make more sense in a RP perspective, How you do you kinda sorta decode the method used to create a singularity or a reactor for that matter?
You know how people always say "this isn't rocket science" well this stuff uhm is "rocket science", if you kinda sorta make a reactor it doesn't just require more concreate and lead to build it just becomes a bomb.