A wallpaper perforator, for the step before stripping. Rollers spinning at different speeds punch funnel-shaped openings through the paper, and the funnel shape is the point — water runs into it and spreads behind the paper instead of sitting on the face. Penetration depth adjusts, because wallpapers differ and the plaster underneath is what you're trying not to damage; scoring too deep turns a strip-and-repaper job into a re-skim. A telescopic handle reaches high walls without a platform.
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