Well, if magnets are being used to help affix to the side rails, I guess they aren't true stainless steel... I could see it if they're used to stick to the legs.
I'm making my own. I've sewn so many things over the years, everything from guitar case bags to costuming modifications. Once I get the material sized to shape, I can't see it taking me more than a couple hours at most.
But I've got something special planned for mine..... muah ha ha ha! (that's supposed to be an evil laugh)