Using utensils, items that open and close by folding. (E.g., folding tables, strollers, playpens, folding chairs, etc.)
Is one allowed to use a serving spoon (without holes or slots) to drain off liquids from solids.
hanging cloth rack, hanging clothes on a tree, etc.
דבר דבר (Dabair Davar): Making Calculations—Understanding the Concept;