Star Trek: Enterprise - EVA Suit Concept Art by  Jim Martin

Star Trek: Deep Space Nine - Bajoran Raider Early Design by Jim Martin

Star Trek: Deep Space Nine - Runabout Concept Art by Jim Martin and Rick Sternbach

The USS Defiant interior as imagined in concept art by Jim Martin with one deck, and as eventually made official by Doug Drexler in the DS9 Technical Manual with 4 decks.

I always liked the way the one with the bridge in the nose looked. It would have been a LOT smaller though

Star Trek: Deep Space Nine - Runabout Interior Concept Art by Jim Martin

Star Trek: Deep Space Nine - Cardassian Shuttle Concept Art by Jim Martin

Federation Relay Transmitter Concept Art by Jim Martin

Deep Space Nine - Attack Ship Concept Art by Jim Martin

USS Voyager Early Concept Art by Jim Martin