To address your other issues:
you refer to attitude control as 6 degrees of freedom ... actually, it is 3 degrees of freedom.
and then later, you ask if a 3-way accelerometer is sufficient? No, it isn't.
To maintain the orientation ( attitude ) of the spacecraft, you need to detect its rotation, and for that you need a 3-axis gyroscopic sensor or equivalent 3-axis MEMS device, plus some means of accounting for the integration error ( drift ) resulting from the sensor readings. On earth the normal way to do this, is to use an accelerometer to deduce the reference direction of gravity, or alternatively a magnetic field sensor, which indicates the direction of the earths magnetic field. Usually both of these are required to prevent the attitude of the vehicle from drifting around some axis or another.
You can also detect changes in the orientation of the craft if you have enough accurate accelerometers at the extremities of the craft to enable you to detect rotating motions, but that is unnecessarily difficult.
You are absolutely correct, I wouldn't try to send a spacecraft to Enceladus with an Arduino and a 3-axis accelerometer
However, are you telling me that the 3-axis accelerometer is not going to be able to sense me tilting a model and thus send a signal which will light my LED's.
I am just looking for simple way to highlight the basic concepts of attitude control. Yes, the real
spacecraft will have control for degrees of freedom, IMU's, startrackers, and a suite of avionics equipment but I am just looking for a simple demonstration.
I was originally thinking I needed an IMU and not just a 3-axis accelerometer, maybe I was just being hopeful because the accelerometer's are so affordable.
Thanks for the help...and patience.