I liked the idea of the Motorcycle Sleeve Vent, which this is based on. I didn't see a way to print it without supports though. I re-drew this in OpenScad. Print with the slats down on the bed. You may have to rotate it. This prints well without supports or raft on my flashforge printer. The vents make the sleeves in my jacket noticeably cooler above 25 mph.

The lip around the front keeps them from going back into your jacket sleeve and your gloves keep them from popping out.