The possibility of gouges on the surface of the HDPE is the reason we didn't use suction cups. We found that even a fairly tiny scratch would weaken the suction so much that even
I could pull the cups off with no problem (and I'm pretty weak!
) We tried a number of different things ... everything from gouges in the surface, to little scratches. We used plain ol' suction cups, and we used suction cups with a vacuum. The bottom line: No matter how tiny the scratch/gouge/mark/irregularity on the surface is, the hold of the suction cup will be weakened considerably.
Anyway, your bot looks great guys.
Good luck!
- Katie