There are some rules for crafting in the Inquisitors Handbook which is a DH supplement (similar to Into the Storm for RT).
Here's the gist of it from what I can remember:
You can either create something new or combine two items into one (like combining the camo cloak with a carapace armor to make super stealthy armor).
- If you just want to combine the items you add the costs together and that's what it costs to make the new item.
Furthermore there is a check penalty determined by how difficult the task is. This is up to the GM but the book gives some guidelines.
- If you want to create a new item the DM makes up some components that the player needs to acquire (with their own costs) and determines the cost of the product that way.
After this there's a series of checks (once again determined by the GM and depening on what you are trying to make, fitting a red dot sight would be one check, designing a building would be multiple).
These checks determins the quality of the result. A simple success may create a product of average quality, 3+ degrees of success lead to a product of good quality and so forth.
There's also a time factor that determines how much time a single skill test actually represents. So once again the single test for fitting a red dot sight would just take a minute whereas a test for designing a building would cover maybe a week of drawing and other engineering stuff.