Make a disc with any piece of material which is big enough and with a hole in the exact center

If you want to make a disc and you have an odd shaped piece of wood, metal or plastic which is big enough this is one way to do it.

Materials:

1. piece of plywood for base board. long enough to be about twice as long as the radius of the largest disc you wish to make.
2. Piece of wood to make the pencil arm, riser, wedge and other parts to lock the pencil arm in place.
3. A few wood screws + nuts and bolts.
4. 4 Base board feet - rubber or felt if you want it to be non-slip.
5. A long thin piece of card.

Tools:

1. Jigsaw.
2. Hand saw.
3. Steel rule.
4. Set square.
5. Screwdriver.
6. Wrench or spanners.
7. Pencil.

Step 1 Make the device part 1

Suppose you wish to make a number of discs of various sizes and for example the largest will be 2' diameter. Let's assume that large discs will need a large center hole.
See the attached diagram to get an idea of the construction.

Your base board should be about 2' long and about 8" - 10" wide.
Draw a line along it's length half way across.
Near one end on this line drill a hole to be a fairly tight fit on one of the larger bolts.
Further along drill another hole for a slightly smaller diameter bolt.
Do the same further along as far as you wish.
Fix your feet to the bottom of the base board.
Cut a piece of timber to form the pencil riser.
Fix it to the end of the board furthest from the first hole you drilled. 

Comments

[I am in the shed!]

Beats my piece of string, nail and a pencil!