I've was able to attach the Snap Circuits base plate to a Lego base plate:
It seems relatively stable and next I'll connect a circuit to Lego.
I received a reviewer's sample of Snap Circuits Motion (from Elenco):
Since the axle on the Snap Circuits Geared Motor (6SCGM) is not compatible with Lego, my first attempt at combining Snap Circuits and Lego is to use the Snap Circuits 2.1 inch Pulley (6SCPULL3) mounted on the Geared Motor with a Snap Circuits 0.375 rubber ring to hold the pulley snugly on the axle. All these parts are included in the Snap Circuits Motion set.
The Snap Circuits pulley will connect to a small Lego pulley mounted on a Lego cross axle via belt drive.
Lego mirror spinner build:
When the circuit is switched on the mirror spins.
This, I think, is the simplest method to get the incompatible toys to work together. The belt drive seems to work well since the mirror does not put too much load on the Lego cross axle.
To the folks out there in Hackaday.io Land (this means you, dear reader), if you have any suggestions for attaching a Lego gear to the Snap Circuits Geared Motor axle (it's too big to fit through the Lego gear), let me know in the comments below.
Controlling the speed of the Geared Motor:
Found a circuit in the Snap Circuits Motion manual to vary the speed of the Geared Motor using a transistor and variable resistor (Project 49 on page 34:http://www.elenco.com/admin_data/pdffiles/753134.pdf).
The following are the build steps:
Thus far I now have a simple method of spinning a mirror and adjusting the speed of its spin.