This is an arthritis aid for a knife more specifically a cleaver.  The different sizes can be changed in the open scad file.

From my initial prints I would change the peg to attach the handle to be the same diameter as I had some trouble makint it fit.  The other issue I had was squaring up the printer on the part where the knife goes.  

Please note 2 rubber bands are needed to wrap around the exsiting knife handle.

There was no design for this however the print did require 55g for the handle and 38 grams for the Knife Attachment.  This led to a cost of 93 cents.