A joinery jig comprising a body and a plurality of spacers, wherein the body defines (i) a first straight slot, a second straight slot and an angled slot, wherein the angled slot connects the first straight slot to the second straight slot to define an elongate angled channel; (ii) a plurality of datum alignment elements aligned with the angled slot, wherein each datum alignment element is spaced from a reference point of the angled slot by a pre-determined distance; and (iii) at least one spacer receiving aperture; and wherein the number of spacers is equal to the number of datum alignment elements and each spacer includes a body having a dimension which is equal to the pre-determined distance defined between a respective one of the datum alignment elements and the reference point of the angled slot; and wherein each spacer includes a body portion which fits within the or one of the spacer receiving apertures.