Rittenhouse Archives has just released The Star Trek The Next Generation Portfolio Prints Trading Cards Series 1 set. In addition to a buttload of autograph cards there is also 1 full color Sketch Card in every case. I've also drawn a small number of those Sketch Cards, 26 to be exact. Each of my Sketches represents an individual episode from the first season, episodes 1 - 25 (1 Episode has 2 cards). Each Sketch has the Season, Episode, and Episode Title written on the back.
I have all 26 Sketches posted in my Sketchcard Gallery for Trekker viewing needs.
And foreseeing the incoming question... yes, the plan is to be doing a full sketch for every Episode of the rest of the seasons to be in future releases.