Medium chance (20% Drop Rate) version. This is a version I personally use and is tested.

A 100% drop rate version, where you are guaranteed to get a Blueprint drop. I recommend only using it if you don't care about balance too much.
Did a small test and it seemed to work.

High chance (33% Drop Rate) version.

Low chance (10% Drop Rate) version.

Medium-High chance (25% Drop Rate) version.

Very High chance (50% Drop Rate) version. Basically a coin flip.