NEW test plate - print it and test if LEGO fits, if not, make wagon 1-4% smaller or bigger and than print test plate again. After you'll find correct size, scale the wagon as correct test plate size and print it !
Remember to come back and post what you've printed as Make.
It's good for the designer and the community (that means you)!
To post a Make, come back to this Thing and click Post a Make.
Or, you can use the Thingiverse Mobile app found on
and the Apple App Store.