to put the lid on the dowels of the cabinet sides

Example such a long benchMake three out of one! We'll do the math for you: A whole chair makes two half chairs, two half chairs and an inserted bridge make three seats.
It's finally allowed, yes even desirable, to procrastinate things. To avoid misunderstandings: It is a stretched bank and not a rack.
Who likes it better, which can shape the inserted portion- and color to match the repurposed chair. We found it attractive, to visibly underline the contrast between the before and the after.

It can also be upholstered – A seat upholstery does not have to hold you back, proceed in the manner described. It will not be sawed through, but taken out. The seat then snaps into place in its support frame. Bring this to fit, by placing the pad on the board and its outline (half each) mark.

With all the technology – with a handsaw (Fuchsschwanz) such a chair can still best be divided into two halves.
Kanthölzer (3×3 cm) in the length of the desired seat – in our example: 1 m – screw against the chair frames from the inside. A gap of 1 let cm, into which a board for doubling fits at the border between the old and new seat. The extension of the frame and the backrest are made of multiplex (18 mm). With wooden dowels (8 mm) in den Hirnkanten verleimen. Die Sitzfläche (also multiplex) Round off the edges with the belt sander, and also on the narrow sides. After fitting, the seat is from below – through the squared timber – screwed, am besten mit Spaxschrauben. Klarlack läßt die Zeichnung des Holzes lebendig hervortreten und schützt seine Oberfläche. Two to three coats are recommended.