From Longman Dictionary of Contemporary Englishsandboxsand‧box /ˈsændbɒks $ -bɑːks/ noun [countable] American English DGOa small box filled with sand for children to play in SYN sandpit British English
Examples from the Corpus
sandbox• The cat used the infield like a sandbox.• The models range from architectural and topographical contour constructions to precise, measured and scaled experiments with steel in a large sandbox. 