We decided to restore 2 chairs.
We removed the old cane from the backs and seats of the chairs.
We bought 1 sheet of Marine plywood which was enough for 2 chairs, top and bottom of each chair .

Materials
One piece of Marine ply wood for out door use - $ 28.85 from Bunnings
We used 8 copper saddle clips, 15mm, at $14.76 a packet .from Bunnings
And, also a number aluminium of pop rivets.to suit the clips

.
Tools
Pop rivets ,jigsaw drill and drill bits Copper saddle clips
Tape measure and pencil
Steps
Step 1
Then I measured the back and seat area of chairs

Step 2
We traced a pattern on the plywood to suit
We roughly cut the plywood around the pattern and then cut the plywood out to suit and sanded ready for painting

Step 3
I painted the cut plywood with Deep Base Deck & exterior
paint; colour blue. Only used a small amount of paint as the area was small and used at least 2 coatings.

Step 4
I allowed the paint to dry at least a day. I did another coat of paint for a good finish.
Step 5
After the paint is dried .we placed the back rest on to the chair and marked the location of the clips and holes for the rivets.
We used saddle clips to hold the back piece on .

Step 6

We used pop rivets through the front of chairs so it looked nice .
Step 7
We fixed the seat of the chairs using some screws we found in the shed to suit the holes already there.
A picture of the completed chairs 
Completed chairs