Battery Wing Nut Wrench
I saw this great idea on an RV forum a while back but couldn't find it again. It's a handy tool to slacken or tighten wing nuts.
I bought a 1/2" PVC T and a 1/2" PVC plug and glued the plug in place then carved the notch in the sides with a Dremel tool.
They probably sell a tool like this in stores but it's quicker to make it than to go looking for one.