We share the restrooms in our hackerspace with other tenants on the same floor. Once a week the cleaning staff does their thing (except refilling the soap, but that's another story), including refilling the paper towel dispensers.
Recently the paper towels started to show up in their packaging on the sink. That led to a lot of waste: towels being strewn around, on the floor, in the sink (clogging the drain) and so on. We were not sure what caused this, but - as good hackers - we tried to make things right by putting the paper towels in the dispenser. Well - not so much.
The (unbranded) boxes are locked with a weird 'key' - maybe also the reason why the cleaning staff can't refill them any more (lost the last key?). Anyway - we set about to fix this armed with nothing but paper, pencil and a caliper. The result can be seen in the pictures below - colourful keys for the men's, women's and handicapped restroom. (Yeah OK: We also used FreeCAD, our Ultimaker2 and indirectly also approximately 100 global supply chains - but who doesn't.)
We left a key in each dispenser and voila - the caretakers understood the (as helpful intended) hint. Now the paper towels are refilled in the proper place again. :-)