Neck block for Dalek NSD, with or without ball bearing sphere

Another thing L3-G0 wants me to making for his Dalek frenemy. Dalek Clara would like neck blocks with the bearings, so here goes.

[L3-G0 met Dalek Clara at ECCC 2014](https://youtu.be/R9TgYUSNmPU?list=PL7uobZWs1n9jPFulJuAT0eQGEJWKDx5R-)

These blocks are pretty close to the information I could gather and should hopefully work for most folks that need NSD neck blocks.

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