Hi, I am really into the magnetic ledges at the moment, I just bought some from the USA (I wish they would start stocking the Magnaturals range in the UK) and paid a hefty delivery fee of $66!!
I've never considered making my own, not DIY skilled enough! But from previous buying of Magnaturals ledges I'd say they are the best for getting a shy crestie to eat, not having to venture far from plantation/hiding spots is a good thing.
I also have a double sectioned food and water bowl on the floor of my terrarium, which is cleaned out regulary by Nacho my crestie!
All in all, if youre confident enough then yea make one, if not I would recommend Magnaturals, they also do amazing hides for geckos that are magnetic too, makes the terrarium look great and all very realistic!