Can I make Osmocote Plus Capsules
Most people buy the 00 size capsules. Making them is extremely boring but saves you some money in the long run. Usually it's easier to just spend $10 on a 100 premade capsules, that will easily last you more than a year. I've nearly 500 gallons of aquariums and go through around 125 a year if I add them every four months.
As a side note, I have heard of people putting the fertilizer pellets in an ice cube tray and making ice cubes out of them. The basic idea behind the capsule is to make it to where you can get the fertilizer under the substrate easily. You could probably even make little panty hose balls filled with the fertilizer pellets, that would allow you to remove the empty cases that seem to never dissolve.