Copy my OpenSCAD files, print the parts and assemble as per the pictures. The most important dimension is the axle spacing which is in the CAD files, and it will require tweaking. There is no need to use my precise mounting "technology": two 1x2 wood blocks. You just need some sort of front and back that is rigid so that once you achieve the right spacing and it's tick-tocking happily, you can lock those parts down hard.

There are a few things to be aware of not obvious in the pictures.

Axle spacing 

...is indeed finicky, but not a showstopper. The pillow blocks holding the escapement wheel's shaft were mounted with wood screws. But:

1. holes for the armature's shaft and pillow block mounting screws were all drilled a couple mm larger than required to allow adjustment
2. machine, not wood, screws were used for those pillow blocks, and
3. wingnuts! You'll want wingnuts.

A moderate amount of adjustment was required, and these points facilitate it.

Pendulum

I used a 108cm 5mm diameter dowel weighing 12g as the pendulum, mounted such that from its tip to the armature's axle center was 110cm. A 1m length should give the expected 0.5Hz pendulum frequency, and I didn't even attach a bob so the CG was only ~55cm.

Weight

I used a spare flange coupler in a pill bottle together weighing 43g as my weight. In the spirit of "minimal investment," I could fasten the weight to the fishing line I used just by closing the end of the line in the cap though a screw-eye in the lid wouldn't hurt.