+ "http://www.ebay.com/itm/161156018270")
+ (make-item "caster standoff"
+ 1 (* 8.2 pla-$/cm^3) 1
+ "3d print at home")
+ (make-item "wheel"
+ 2 (* 11.3 pla-$/cm^3) 1
+ "3d print at home")
+ (make-item "deck holder"
+ 2 (* 4.0 pla-$/cm^3) 1
+ "3d print at home")
+ (make-item "sonar holder"
+ 2 (* 2.4 pla-$/cm^3) 1
+ "3d print at home" "price of filament is an estimate")
+ (make-item "motor mount"
+ 2 (* 3.1 pla-$/cm^3) 1
+ "3d print at home")))