Give Her What She Asked For
Men really need to spend less time assuming things about women and more time doing their actual job. Imagine going to the store to buy something and getting subjected to mansplaining instead. All this OP wanted was some epoxy paint but the guy at the store first explained what it was for and then told her they don’t have it.
When her brother went in just 5 minutes later, the same guy magically found the product. When questioned about it, he said that it’s a complicated product and he wasn’t sure if she’d be able to use it properly. The irony is that her brother can’t even tell the difference between a handle and a roller and was still given the epoxy paint, no questions asked.