1. Prepare the required materials: make letters with paper or cards. Prepare a large piece of paper or card as the bottom plate, and cut another piece of paper or card into letter shapes.

2. Draw letter shapes: On another piece of paper, draw the shapes of letters "plus sign" and "oil". You can draw the outline of letters on paper with a pencil first, and then cut them out with scissors.

3. Layout letters: put the bottom plate on a plane, and then put the letters "plus" and "oil" on the bottom plate according to the design intention. You can try different arrangements, and adjust the spacing and relative position between letters as needed to achieve the desired effect.

4. Fix the letters: Once you are satisfied with the layout of the letters, you can fix the letter shapes on the bottom plate with glue or scotch tape. Make sure they are firmly attached to the bottom plate to avoid moving or falling.