This jig can be used in two ways:
1. As one body to put on a board - this way you get spacing and holes will show you where to drill. You can use triangle cutouts to align on a chalk line or a laser
2. With sides broken off - then you can use triangle cutouts to guesstimate center when screwing down board cut under angle on the end. The broken off pieces can be still used as spacers.
The attached STL is for 143 mm wide and 28 mm thick boards with 8 mm spacing. To create your own, just edit the spreadsheet in the FCStd file.
The author marked this model as their own original creation.