Build your own Variable Lab Bench Power Supply from Printer Adapter 

How to Make a Variable Lab Bench Power Supply from Scrap Printer Adapter
Things Required :
1) Plywood
2) Scrap Printer Adapter
3) Digital Voltmeter : amzn.to/3m3Z7Yu
4) Power Cable : amzn.to/3aZchjb
5) 9v DC Power Supply : amzn.to/3E7Khqd
6) Motor Speed Controller : amzn.to/3vAr7pR
7) On /Off Switch : amzn.to/3m2RZM8
8) Banana Plugs : amzn.to/3nfodDh
9) Male Power Connector