A very productive weekend of digging uncovered these sci-fi paperbacks among others including three with covers by Richard M. Powers to add to the collection (I’m not so interested in the content, just the covers). The SF-18 cover artist is uncredited but a quick web search reveals that it’s by Dean Ellis and the original art is actually available to buy from this site if you have $5.5k! I’ve screen-grabbed the original below.

The Harlan Ellison book is an oddity as I noticed it shares a version of the same image on the cover of the Elektriktus album Electronic Mind Waves.

UPDATE: It seems that the image used on both the Ellison and Elecktriktus albums was originally by Rayment Kirby, entitled ‘Watch it’ and was printed as one of the first ever posters from the Big O Poster company. I contacted him and he shared his memory of making the piece,
“It was made by cutting out a B/W print after masking out the model’s hair and hand colouring it . It was laid on black polythene sheeting and the clock parts glued in position and the strands radiating from them were made from Bostick like glue. I think I shot the image in the late 1960s to early 70s so it was a long time ago. I don’t even remember who the model was. Having thought about the picture I think the poster rights may have been sold by an agent I had at the time. This would not have Included the other uses that (have) been made.”