
Replaceable blade knives
The skill and time required to sharpen dulling knife blades is a trouble too much for most people nowadays. There is a wealth of very reasonably priced new and very sharp blades, most of which keep their edge well. A similar huge range of handles is available to take these blades and store a fresh supply. The increasingly popular snap-off blade can be "resharpened" several times (13 on the 9mm snap-offs).
Heavy duty knives
Knives with 18mm snap-off blades
Knives with 9mm snap-off blades

Trapezoidal sliding blade ~ plastic ~ by Stanley
$0

Trapezoidal sliding blade ~ metal ~ generic
$0

Scalpel handle ~ SM No3
$2.12

Pencil knife ~ plastic ~ five blades ~ coloured
$2.44

Pencil knife ~ metal ~ colours
$3