Posted: 28/01/2016 at 07:51
Make the container as light as possible without losing strength.
You need only three clips for larger tools on the outside.
Make it waterproof
Weight test the wheels on grass - a loaded box leaving ruts or such like behind will be quickly discarded
Add value by making it able to be sat on or stood on.
If I have to use a wheelbarrow how will I move both its at the same time (persuade me to use your box rather than just putting stuff in the wheelbarrow.
Don't make it big enough for everything - just big enough to carry a sensible percentage of our tools / kit
Good luck and ignore the ne'er sayers. Only by doing something will you find what's right.