>>11014855If the wheels can be in line with each other I'd try a gear case like pic related. The two axles butt against each other inside the gear case but don't connect; the white bushing is just for stability. It's also much easier to stack and design around this mechanism since you're not worrying about the distance between horizonal gears. The only thing is everything is offset from the gray column's grid by half a stud. You can either roll with that or offset the column with jumpers to get the shaft back on-grid.
