I was responding to the original question as stated. Scraps of paper are unwieldy and difficult to shuffle, and I wouldn't know to obtain a tile-size dry erase slab. Those suggestions don't seem like they would be illegal, but they do seem like even more impractical uses of one's preparation and game time.
Like TheLamb, I too scribble stuff on my scoresheet (and sometimes put alphagrams or potential plays in the ISC command line.) That should ideally be only an adjunct to a mostly mental play-finding procedure, if you aspire to expert status. I don't even shuffle much now.
NASPA (CSW) 1876, WESPA 1930
Virtuals Champion, April/May 2015