Putting the first card in is a little tricky, but after a little while everything comes together. This is the geometry of the tabs that fit into each slot. Next I insert the last card. This brings the support into shape. Now adding cards is easy.
Work goes quickly.
Completing the entire assembly takes only about 15 minutes. Here's the final surface. I like some parts of it. I'm starting to wonder about other ways of connecting parallel cards. The scored edges of the cardboard are a nice brown color.