As a feature, you can disassemble your HDD and mount a dozen of short poisonous needles on every edge of your HDD. It is to note that a spare space allows to use syringes, so you can use HDD multiple times.
Also, you always can buy a broken or obsolete HDD for no more, than 5$ (or only 3$ in bulk) or just try to buy some as scrap on local recycling factory for some loose change since you will need only aluminum cases.
In USA, it is possible to buy obsolete or broken PCs in bulk for only 2$ each, so you can provide yourself with a good supply of HDDs from them, as well as lightweight FDDs and CD-ROM drives, which also may be turned into throw weapons.
Also, you can use HDDs (as well as CD-ROM drives and FDDs as padding for anti-bayonet armor. Nornally, you simply need to get an utility vest and fill it with both 3,5 inch and 5,25 inch drives as pads.