Um this does sound like a BRILLIANT idea, but I wouldn't suggest anyone do that and here is why. As someone with SEVERE food allergies there is a risk for cross contamination. Sure I would hope that someone would bring a CLEAN measuring cup with them but the next person to use the same bin could be allergic to an ingredient that was used in the detergent the last person used to wash their cup with.
Also, if someone made peanut butter cookies and doesn't wash their dishes properly and decides to take their measuring cup to Bulk Barn and stick it in the bin with chocolate chips it could be very dangerous for the next person. Just something to keep in mind.

