The Towel Line
Why this drill
A rolled towel laid along the putt line is instant path feedback: the putter head traveling straight brushes past it evenly; a cut or in-to-out stroke bumps it. Cruder than a training rail, free, and always in the closet.
Setup
A bath towel rolled tight and laid in a straight line on the carpet. Ball placed a putter-head's width from the towel's edge, parallel to it. Five balls, a target down the line.
The drill
Fifteen strokes keeping the putter head parallel to the towel back and through — the gap between putter and towel should stay constant like train and platform. A bump or a drift wide is a path error made visible. Watch the putter, not the ball, for the first ten; then five watching nothing, feeling the corridor. Pair it with the carpet gate on alternate evenings: path one night, face the next, and the stroke rebuilds itself.
One thought to take with you
The putter rides the rail — same gap going back, same gap coming through.