1. 25 nut bolts
2. 4 big nut bolts
3. 1 old mobile phone charger 5volts and 500mA (that you don't mind destroying)
4. 1 metal plate (that you don't mind destroying)
5. steel wire (around 5 feet will do)
6. 1 used coca cola plastic bottle (2 liter preferably )
7. 1 12 volts dc motor
8. 1 jam bottle (250g) cap
9. 1 pvc pipe (around 15cm will do)
10. scrap electric wire (20 cm)
3. Metal cutter
4. Paper cutter
5. Drill (You can always drill a hole in pvc pipe by using a hot nail if you don't have a drill, also use nail and hammer to drill holes in metal sheets)
6. Screw Driver
Step 1: Making outer ring
To mark where to drill holes in the ring, what you can do is trace the ring from outer edge on a paper.
Now you have a circle but don't know it's center. So make two random chords on your circle and make perpendicular bisectors on them. Perpendicular bisectors from them meet at the center. Now you can easily locate the center and can use a protractor to make spokes from center to circumference such that they are 30 degrees apart.
Drill 12 holes in the outer edge such that they are 30 degrees apart from each other.
Make sure that sharp portions of stainless steel plate are properly dulled as soon as you finish cutting it to avoid any injury from sharp edges.
Caution: Be very careful while using iron cutter and don't cut your fingers as it hurts...........a lot!