Ron-Using accelerometers in 3d space will soon become inaccurate due to
small errors in the accelerometers, math rounding errors and drift. How
do you propose to 'erect' such a device to keep the shiny side up?

The only constant acceleration is the acceleration of gravity. A "leaky
integrator" with a 2 or 3 second Tau should work fine.

If it can be done mechanically, it can be done electronically.