This one is pretty straightforward all that is needed to make this is a couple of 484mm length strips of 32 mm X 20 mm X 4mm angle aluminum. the jacks are 22mm apart, the notch cut out at each end is 20mm. Start by finding the centre 242mm in from each end, measure 11 mm each side of centre then 33mm, 55mm, 77mm, 99mm, 121mm, 143mm, 165mm, 187mm, 209mm, from each side of centre. The last marking on each side should be 33mm from each end. Centre punch the markings and drill them with a 3mm or 4mm drill bit, then drill them out with a clearance drill bit for the jacks. After this cut out the 20mm notches at each end. Then solder leads to the jacks and install them. Note before drilling holes placed the jacks on the back of the aluminium strips to assess if the jacks are going to be in the right positions with clearance and no overlap.
Click on the above pictures for a closer view.