Ukulele builders in a guitar building supply world... I think the quarter inch (0.250) stuff is probably perfect for a dreadnaught but way too big for an uke. 3/16th ( approx. 0.190) is better as Gary said. However maybe top depth of 0.060 is easier than the 0.070 since you can get a router bit with a stop on it in that size and maybe better proportioned too...? Mostly just a question of taste? Probably just trivial after all.