When I lived in San Francisco in the early 80's I modeled for a group that called itself a "gay mens erotic sketch class". The class was a group of 20 to 30 gay guys with variing degrees of talent who would meet a couple nights a month to sketch a nude model. There was usually a different model for each session. The classes were held in the "instructors" loft off of Folsom street. The erotic part was the model was suppose to stay hard while on the posing platform (before viagra) which was not always easy to do. Sometimes the sketchers would come up to the platform for a close inspection of the body parts they were drawing. I modeled for several sessions. One of the sketchers gave me a copy of the sketch he made that I still have. Got few other modeling gigs from the class and made a few bucks.
That group is still going. I have modeled for them as well. Was a lot of fun and nice to see drawings of yourself. I also belong to a different drawing group in San Francisco. We take turns drawing each other. I like it much better.