My inspiration for this strip was to have the characters find themselves depicted as demons in a painting reminiscent of the hell portion of "The Garden of Earthly Delights" by Hieronymus Bosch. The catch was, in order for the gag to work, the final panel had to really look like a painting of that style. That meant figuring out the most time-effective way of pulling off something that could pass as a detail of an oil painting.
The first attempt was a 12x12" canvas with acrylic paints. I didn't get far in before I realized the layers of paint needed meant a lot more time going into it than expected - and that I lack the tiny brushes (and skill for detail) to pull this off. Rather than give up, I switched methods. This time I whipped out my watercolor pencils and drew a version of the scene I wanted. It wasn't looking great, but I thought I could fix it - so I brought out the REAL watercolors next and started dumping more layers on it. Eventually, I worried the piece was getting muddy, so I went in and used a black tech pen to sharpen some edges. The result was the piece you see above.
At this point, I was committed. I had put most of one day's work into one panel of one strip for a gag that iffy at best - but I was not about to throw it all away! The brush stroke effect wasn't really there, the composition was too hokey and the background colors weren't deep enough. To fix that, I turned to Photoshop. Right away, I suffered the consequences of leaving the entire piece too light, as every little tweak drained the lighter details away. I tried a few filters to make it look more painting-like, but got mediocre results. The final version ended up with me throwing the watercolor filter in over my original watercolors and adding some shadows. I'm not sure how effective the result is for the final strip, but it's all I could do with the piece I created.
Maybe I should have gone with a throwaway gag about the gallery coffee shop instead...