A drug delivery device or patch-like delivery device which employs a spring force and an inclined surface to apply pressure on a fluid reservoir, thereby delivering medicament to a user's body. The slope of the inclined surface may be engineered to control the drug delivery rate. The device may be low profile and wearable, for example in the form of a patch. A visual indicator of the amount of medicament delivered or remaining may be incorporated, for example via a transparent window that shows the progression of an inclined surface as it presses on the reservoir. The device may incorporate mechanisms for automatic extension and retraction of a cannula at the beginning and end of drug delivery. Drug delivery rate may be limited with flow restrictors, and by using a two-reservoir system with a viscous liquid displacing a reservoir containing the medicament.