I've had a misfortune to buy this 3V-7V Light Shock Absorbed Smart Robot Tank Chassis Car DIY Kit With 130 Motor.
The thing comes with no specifications whatsoever. There is no information on how to attach anything to it.
As you can see, there are 3 spacers coming up from the bottom of the chassis: 
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I had to figure out the layout of the spacers and how they relate to the rest of the tank.
The proposed TankTop2.dxf file (created with QCAD) is my answer to this issue.
The holes are marked with metric diameters, but I actually used nearest imperial drills.
The spacer furthest away from the motors is quite a bit higher than the other two, so I had to drill a large hole to let it through my top. I used 1/8" PVC board for the top. With that, I ended up adding 3 washers under the top to level the board on the high spacer with the two low spacers.
I printed the entire drawing on an index card, then taped it to the PVC board and drilled the holes through the card.
I used M2 screws and an M3 washer under the screw for the large hole.
This is what the final result looks like: 