You will need basic woodworking skills and access to common woodworking tools.
Bertil Chair and Ikea supplied fixings/hardware
1200mm x 400mm x 22 mm plywood sheet
1200mm x 45mm x 20mm pine
1200mm x 20 x 20 pine
Scrap bits of pine
PVA wood glue
Step 1: Halve the Chair
Work out which rails need to be cut in half.
Measure them to find the centre.
Saw them with your preferred timber saw.
Step 2: Assemble the Two Halves
I glued all the joints to provide extra strength.
Step 3: Mark and Cut the Seat
1200mm (or about 4 feet) provides seating for 3 people and fits my dining table.
I used the Bertil seat as a template to trace the ends of the bench seat. The ends are angled back, are notched around the back of the chair and the corners are rounded.
Cut with a jig saw. (tip: flip the ply over so that the top will not chip during cutting)
Sand the edges down.
Step 4: Glue'n'Screw
Use the provided brackets to attach.
I added some pine mounting blocks to the ends for extra strength. Just glued and screwed.
Remember to pre-drill pilot holes so the pine blocks will not split.
Step 5: Under Bench Rails
Just glued, screwed, clamped and while clamped, pine mounting blocks attached.
Step 6: Paint.
I may paint the chair ends a different colour...not sure yet