If you're not sure, search on 'Ender 3' or 'Prusa MK3' or 'CoreXY'. There are any number of examples out there to use as inspiration. Also, since you should include at least some portion of a printer on the cover, it should really look like a 3D printer, not some nondescript or weird 'what is that?' machine. Not necessarily one of those, but I hope you get the idea - ACTION, CREATION, INNOVATION. Or Mister Science with an illuminated light bulb on his hat with tools in his hand busy putting one together. Or a wizard waving his wand to make one appear.
I want to draw people in, have the imagery show ACTION (see the three covers I selected in the 'Design Inspiration' section.) Like a sculptor making a 3d printer out of a block of granite. Looking at the early returns, they're kinda missing the point about empowerment.
