No matter how many times you "prototype" the cactus armour, you always have to return to an alchemy engine to craft it again.
Steps to Reproduce
1. Prototype Cactus Armour 2. Attempt to craft another away from an alchemy engine
1. Prototype Cactus Armour 2. Attempt to craft another away from an alchemy engine
A developer has marked this issue as fixed. This means that the issue has been addressed in the current development build and will likely be in the next update.