I have a few of these in my favorites and it is on my to do list. These SketchUp plans are my blueprints which can be downloaded here.
The Dimensions are in Scene 2
The detail for the hole position is in scene 3. “Paul with his “X Puzzle - 3 times a charm gave me the insight for this method. Use a kerfmaker (see my quick 5min kerfmaker) to cut out the centres of solid blocks. Put the two together and drill the holes right thru from the end. This ensures a perfect alignment for the pins. I have a few pieces of 5mm aluminium rod lying around so I plan to use that for the pins. Wooden dowels or nails could also be used. Adjust the hole size for whatever dowel will be used 5 or 6mm will work with the dimensions of this model. The pins should be about 2mm shorter than the recess holes in which they fit.
-- There are some things that money can't buy - Manners, morals and integrity