posted 12-01-2018 06:48 PM
A McDonnell Aircraft artist named Anthony Tharenos did the artwork for the Gemini 12 patch, as well as a version for the Gemini 12 backup crew. See the Gemini 12 page on my site for photos, one of which includes a handwritten note of appreciation to Tharenos from the Gemini 12 crew.
As webhamster mentioned, John Young's wife Barbara (who was a professional artist) designed the Gemini 10 patch.
In the Vol. 23 No. 4 issue of Quest magazine, Amanda Wegener posits that Neil Armstrong did the basic design for the Gemini 8 patch, backing this up with sketches from his personal papers. (My only reservation about this theory is the marked variation in quality between the "billiard table" sketch and the "spectrum" sketch. Just because the sketch is among Armstrong's papers, doesn't prove he executed it. On the other hand, since I haven't had any success in my attempts to contact the archivist at Purdue, Ms. Wegener may well have further information that backs up her theory. I'm assuming that to be the case for now.)
There is evidence that William Bradley designed, or at least did the artwork for, the Gemini 7 patch. Bradley worked for MSC film subcontractor AV Corporation.
According to Mr. Tharenos, most of the artwork for Gemini patches was done by artists in McDonnell Aircraft art department. In addition to his own design for the Gemini 12 patch, he provided an image of the artwork for the Gemini 5 patch that carried a McDonnell Aircraft photo lab stamp (again, see my site).
That's about all I have to add. I wish I knew more.