Here's an answer from one of our followers on Twitter.
Hope this helps!
Drill appropriate sized holes through two 2x4x18" at about 3" OC. Rip the 2x4s. Attach both with hinges. Attach each one to the wheelbarrow handles, being sure they're aligned. Put some kind of latch at the opposite ends from the hinges.
Put the tools in the holes with the tool ends opposite each other, and the tool end vertical to the ground. Put the tool as close to the holder as possible to keep the center of gravity as close to center as possible.
Awesome. I do better with pictures and illustrations. Any chance of sending a photo?