Step 1: Load blueprintSelect blueprint:
You can find downloaded blueprints in C:\Program Files (x86)\Steam\steamapps\workshop\content\387990, and your own blueprints in %appdata%\Axolot Gaming\Scrap Mechanic\User\User_...\Blueprints.
Step 2: Get the mods!
What is this?
X's Required Mods Finder (XRMF) is a small web-based service for checking the mods that you need to load a blueprints. It knows all the blocks and parts of more than 200 popular mods, adding up to about 5500 blocks in total.
XRFM is also integrated in Brent Batch's Blueprint tool.