The first of 14 spars - the fore lower mast.  They will all be made in the same way.  First, four long square pieces will be glued together to form a larger square.  Here, two pairs of two square pieces are being glued together.  The strong back is being used to ensure that the pieces are straight vertically.  An additional support (red circle) is used to ensure that the pieces are straight horizontally.  The same little wedges used on the gunwale are used here (green circle).