Sphero Opening tool

Add some 608 bearings, Push a pipe cutting wheel into the seam from above (I mounted mine on my CNC because I'm lucky enough to have one) and then turn the sphero on the bearings, advance the pipe cutter, turn, repeat. Eventually you'll either separate the seam or cut a neat channel through it - Much much easier to glue back together than using a dremel, saw etc.

Love little robots, hate putting them in landfill because their LiPos are end of life!