openSCAD
Add text and logos to your openSCAD files with no faffing
[EDIT: Quite a lot of this post has been re-written, as it was pointed out to me that the text() module was inbuilt, and that perhaps I shouldn’t try doing this stuff in the middle of the night after entertaining an 8 month old all day. I have re-written this post rather than take it down because I’m always pleased when people point out a better way to do things, even if it does make me swear because I spent ages looking for the simple answer and couldn’t find it.]