Blankets
Sam sent the team away after a break.
Meanwhile, he sat down in the centre of the base at a certain spot.
He took out a bunch of scrolls and spread them on the ground. All of them combined created a map of the areas they have already explored and Sam started drawing the formations he made the team members put up.
Even though Sam noticed that he cannot place the formations himself and appear to be making dumb mistakes when he used normal nodes or any other material as nodes for that matter, he also figured that if he used his subordinates as the builders of the formation and all he did is draw the formation on a paper, there is no problem.
All his skills disappeared. His arms are magically becoming clumsy when he is setting up a normal formation, but the knowledge is not disappearing.
He can utilize his knowledge but not skills.
This actually didn't take much from him in this aspect.