Bit-by-bit, little details emerge about the production of the 1968 Topps 3-D Baseball set, which as intrepid readers here know, I consider to be one of the finest limited releases sets ever put out by the company. Prototypes, thought to be created specifically for Topps (more on that momentarily) were prepared by Visual Panographics of New York City, using a process they dubbed Xograph. You've probably seen a reference to both on the backs of the Kellogg's cards of the era.
It's those Kellogg's cards that muddy the waters a tad but everything I've ever seen in various auctions and writings of knowledgeable collectors indicates the 1968 3-D's and their various prototypes and proofs were prepared for Topps. So while things like this could theoretically fall into the category of "attributed to Topps" without more evidence, I think it's safe to call the prototypes and proofs Topps items.
The issued cards have their quirks but like many scarcer Topps products, were born in a retail test pack:
Which in turn came in a box that was likely plain, with a just a price sticker affixed.. A retail box was designed but in all probability never used:
Note the lack of a commodity code on the box bottom, which sometimes happened as sets and marketing were being developed. This lack of a code would also sometimes occur for items produced by a third party. The 3-D cards were designed to catch the eye and looked like this:
The Xograph logo is prominent in the lower left corner and the design would clearly be refined and form a template for the 1969 regular-issue Baseball cards. The reverse is blank, as this partial test pack content shows:
I wonder if that means this style of stamp, with its larger all caps "title" line, indicates a true proof vs. a pre-production concept sample? Or perhaps it was a door opener made up by Visual Panographics.