Hi, I'm really glad you're enjoying the game!
Each Item can be used once per purchase. It should be possible though to buy more than one Rekonstruktor on a single planet but you must never use the same Rekonstruktor twice.
The printer-friendly sheets are a great idea! I'll get to that soon 👍
The multiplayer version is on my "to-do-list of shame" but maybe one day it'll be released ✌️