Fingerprints; invisible ink; writing on one skin; x-rays.
Does One Have to Use the Dishes That Are in Their Closet, or Are They Allowed to Wash Dishes From the Sink?;
Using nice smelling liquid soap, placing lavender flower bars and other essence of deodorizers into drawers or closets, and putting unscented powder into shoes...
An adult shaking a rattle for a baby and using an alarm clock on Shabbos;