When Ulta switched to the smaller/more expensive bottles for their salon line, they clearanced the old stock so I bought a few polishes to use in frankens. Today I've got the first frankenpolish to result from that purchase, a simple combination of Studio M Decidedly Devious (an extremely dark blue creme) and Ulta Piñata-Yada-Yada (a multi-glitter in a clear base, similar to Deborah Lippmann Happy Birthday; I did a comparison here).
Decidedly Devious is pretty pigmented on its own (it's nearly a one-coater for me), but the clear base in Piñata jellied it up enough that I needed three coats of the franken for full coverage. Since it was sheer-ish, I experimented on my ring finger with two coats of the franken followed by one of Piñata followed by one more of the franken. It turned out that the layering didn't look too different from the franken on its own; a bit more glitter density, perhaps.
I'm really happy with the depth to this, the glitter submerged in the deep blue at different levels. It reminded me of stars and planetarium shows, so I named it Lost in Space.
I don't have Deborah Lippmann's Forget You (yet) but based on swatches I've seen of it, this franken is its cousin—the glitter is a lot more dense in the Lippman, and the base is true black.