I've created an assembly for a small handheld electronics device. and i now want to create a casing (silicon) to go around the device, i am still quite new to this software and can not find a solution, im sure its a simple soloution but i definatly need help.

What i want is a casing about 2mm thick that is a tight fit around the device but isn't the same shape. I want the casing to change the look of the design. If someone could help me with this i would really really appreciate it.

Thanks

attached in the device that i want to incase.