- Calculate half the measurement of the longest line. In this example the long line is 340mm and the short axis is 200mm long. So the diagonal is 170mm.
- Measuring from the end of the shortest line, mark off this amount on the longest line, top and bottom. You can use a ruler or compass set to the correct length.
- Insert a pin at both these points.
- Place a piece of thread, string - or in this case a quick release tie - round one pin. Tie a knot in the thread at the far end of the longest line.
- Put a pencil inside the loop. Pull the thread taut and begin to draw the oval.
For a leaded panel, the space occupied by the lead came will need to be accounted for in the measuring of the dimensions.