The blank is secured to the pine faceplate by tape and screws.
A prominent "danger ring" is drawn just outside the cluster of screws.
The surface is turned to a shallow cone, so that the edge is very thin.
The central hole is 100mm in diameter. It will be bored through to the faceplate.
The hole is nearly right through, some of the red warning paper can be seen.
The screws and central plug have been removed, but the rim is still held by the sticky tape. Sand and polish.