The present invention relates to a mould for forming a joint spacer device or a part thereof, comprising: at least one rigid container body (2) provided with at least one first perimeter profile (5) delimiting at least one first moulding surface (6) intended to shape at least one first portion of the joint spacer or a part thereof； at least one rigid cover (3) provided with at least one second perimeter profile (7) delimiting at least one second moulding surface (8) intended to shape at least one second portion of the joint spacer or a part thereof； the rigid container body (2) and the rigid cover (3) are engageable in a removable manner to each other, at the first and the second perimeter profile (5, 7), so as to delimit a cavity (4) corresponding to the external configuration of the joint spacer or the part thereof. The mould comprises weakening means (18) on the rigid container body (2) and on the rigid cover (3) so that they are separable into parts to allow the extraction of one spacer device or one part thereof, moulded therebetween.
