Trying to figure out if I can use a dry erase marker for recreation and then erase whatever I wrote. Is this allowed?
It is forbidden to write, even temporarily on Shabbos. R Jack Abramowitz from OU writes
Koseiv [writing] involves creating any meaningful letter or symbol. It doesn’t have to be with ink on paper. A rubber stamp, carving into stone or cutting a letter out of paper all involve koseiv. Even forming a letter out of something temporary – such as those toys where one uses a magnet to manipulate iron filings – is prohibited on Shabbos under this melacha. Koseiv applies to letters or symbols in any language, including Braille, Morse code and the like. [...] Temporary writing is prohibited rabbinically.