Please note that casting is a potentially hazardous activity. Observe appropriate safety precautions. The details should be covered in whatever casting training you received, whether online or in a class.
In this instructable, we'll erase the disk by melting it. Hard disks are mostly made of aluminum, which can be recycled, so don't throw it out! Instead, we'll cast a new solid-aluminum hard disk using the original as a pattern. For this project, we'll use the aluminum foundry at TechShop Raleigh-Durham. That way we have all the casting tools we need, including sand, furnace, flasks, and molding tools.