Hello littrella, sorry I have not gotten back to you before now.
It has been a VERY long time since I have checked in here on the Forum...
Are you talking about the training "chariot" I use in between the travios and an actual cart? Yes, my Hubby made that, he is extremely handy.
I can't say I have ever seen anything like it either. Are you looking for one to train Minis to drive with?