Cutting Out the Pieces
Ragged edges are the enemy of these puzzle pieces, so I took two preemptive measures: First, I drilled a tiny hole in the center of a large piece of scrap plywood to act as zero-clearance support around my scroll saw blade. Stick this backup board to your saw table with a strip of double-sided carpet tape.
The contours of these puzzle piece shapes certainly aren’t intricate fretwork, but I still selected one of the finest-tooth blades available for my saw: a 5R 12.5 tpi reverse tooth. It left clean, crisp edges on both the top and bottom faces of the pieces — exactly what I wanted. Instead of cutting the puzzle pieces out one at a time, I sliced off a row of four from the larger blank and cut the row apart. Just bear in mind that it’s more important that your puzzle pieces have smooth, flowing edges than that they follow the pattern grid exactly. Keep the puzzle stock moving through the blade in one continuous operation, and don’t stop. Hesitation can lead to rough edges.
Making the Frame Parts
The puzzle’s frame consists of a base piece of plywood or MDF wrapped with rabbeted and mitered rails. Cut your base (piece 2) to size. I made mine about 1/32″ larger in length and width to provide a slightly looser fit around the puzzle pieces when they are assembled. Sand the faces of the base up to 180-grit.
The long and short frame rails (pieces 3 and 4) are only 1/2″ thick and 1″ wide, and they require a 1/4″ x 1/2″ rabbet to fit around the base. That’s not a lot of stock between you and a spinning dado blade. So, I made my rails from wider material for safety and ripped them free. To prepare the saw for milling the dadoes, I buried my dado blade partially into a sacrificial fence clamped to my saw’s rip fence. Raise the blade to 1/2″ and extend it 1/4″ out from the fence. Install a featherboard in the infeed side of the blade to keep the rail stock pressed firmly against the fence when you make your cuts. I also used a thin push stick engaged in the shoulder of the rabbets to feed the wood over the blade. After rabbeting, cut the rails to final width.