Is it permissible to play with lego on shabbos, and what is the mekor.
Answer:
It is permitted to play with lego on Shabbos, in particular where the purpose is not to leave the construction for a long time.
For lego that will be left for a long time (sometimes true for small lego), one should be stringent.
Sources:
Where pieces are not fixed in place strongly, and it is normal to put them together and take them apart, it is permitted to play with lego (Minchas Shlomo 1:11).
See also Rabbi Pesach Eliyahu Falk (Shut Machazeh Eliyahu), who is likewise lenient for matters of boneh, but is stringent with regard to small lego because of the issue of “writing” (sculpting).
