Sometime in late 1966, Creative Playthings must've gotten itself a marketing guy, or maybe a lawyer guy, because all the toys that're called things like Thin Arch in the '66 catalogue are called things like Arc-Curves TM in the '67.
Either way, these 11x2.75=inch arches of molded plywood "will take the same punishment as unit blocks." As the catalogue says, they "can become the base for bridges and tunnels, or arches for building store fronts."
Or they can become the $6.75 substitues for the Naef Rainbow Arch blocks, which cost approximately $1 million, though their xylophonic properties are unknown.
