Hi do you have any wheels encoders recommended for this robot ?

Mine came with the backs wrapped in a thick plastic sleeve that covers where the wires are soldered (you can see it in the pictures above, too). Is that meant to stay? or will it melt?

I would be afraid to buy anything from DFRobot if that how support is trained. Have you thought that it may not be possible for me to use the 3D model without significant effort and installation of software? Why not simply give an answer of rough dimensions, perhaps even update the product listing with them? If I go on Amazon, I don't know of a product that is listed which doesn't provide a basic reference of its size. No one even has to ask. Don't cover your product listing deficiency with a demand the customer has to do something else to get an answer.