where can i get 2d techincal drawings ?

Why do you need drawings for practice??? Look around you and try to visualize in 3d the stuff that is there, this is the best exercise you can imagine...
only need an item and a measuring tool....
And remember that engineers are the one who produce the drawings themselves......

guitar models for design :

http://notrightinthehead.net/2012/03/24/free-guitar-pdf-blueprints/

here in this link has mech drawings
https://www.facebook.com/MechanicalMachineDesign/photos_stream

Connecting Rod Drawing in 2D .Dwg File

Check my recently posted Drawing about connecting rod

InventorWizard : http://www.inventorwizard.be/blueprints/index.html
RS Components (drawing associated with products) : https://befr.rs-online.com/web/