everyone complaining about MC's otherworld tech ideas needs to realize she would only really have access to the IDEA of it
but still have to reinvent it from the ground up. she'd have to figure out- how the item works, what the items made of, if she can manufacture similar parts, if not what can she subsitute for it, if monster parts would be compatiable to her idea, what enchantments and magic stones would it need to compensate for the electricity she was familiar with?
even with the waterproof cloth- technically that's vinyl. but vinyl is a chemically manufactured plastic. her version is cloth treated with a blue slime powder coating.
her past may havr given her the idea but thats a different item with the same purpose. and if its the same item its still a new variety you'd be able to repatent yourself because of the fundamental differences in make.
as shown someone with actual creativity can challenge her know how and make a product similar to our modern items with zero hints.