A. Michael Dresdner: "What you seek comes in both plane format and in a hand-held edge tool. Sometimes called a round molding plane or easing plane, the more common iteration is a smaller-handled gizmo called a cornering tool. In the old days, cheap, stamped metal versions were given away free by many companies as premiums. I used to have several with advertising on them. For a good quality cornering tool in hand-held or plane format, check out leevalley.com. Do a search for "planes" under the woodworking button, and then click on "molding planes." Two versions of cornering tools and one plane format tool will pop up."

A. Rob Johnstone: "They are called radii planes. You can find them at rockler.com or any number of catalogs. Most have replaceable blades and work best on long straight edges. For curved edges I prefer a router bit (sometimes called a roundover bit) with a bearing to guide it."