Oh. The plugin you’re looking for is either a sampler or a drum machine. I prefer samplers, there’s a handy one comes with Reaper called ReaSamploMatic.

Either find some free VST plugin for a drum machine on the internet, or make one yourself using the sampler and some free samples off the internet.

I’ll explain how I do it and used to do it.

There’s a few ways to do that, my preferred way is this, it’s a bit hard to draw but it is way easier for mixing:

1. Create a new track, name it Drums
2. Create a few more tracks, each for Kick, Snare, HiHat, each for toms and your preferred cymbals.
3. On the Drums track, there’s a button on the left lower side of the track that looks like a plus sign on mouse over, clicking it will make Drums track a folder for all tracks below it.
4. In each drum track you’ve created load the ReaSamploMatic plugin, and load drums samples (that you should have downloaded somewhere, it’s easy to find them especially on reddit) into the plugin.
5. Pretty much done. Ctrl+click+drag on the timeline will create a roll, double click the roll and draw the notes within.

Now save the Drums folder as a template for future use.

A bit more easier setup, but I find it lacking a bit during mixing:

1. Create a single track called Drums
2. Load multiple ReaSamploMatic plugins into it
3. Load samples into each plugin
4. Configure each plugin to use specific note on the piano roll, so that you can draw the entire drum kit midi inside a single roll, usually it’s the setting that has a range of note X to note Y.
5. Create the roll, edit the roll.

Your best friend soon will become Kenny from REAPER Mania YouTube channel, he has a truckload of extremely valuable content about reaper and music production, here’s one of the vids about creating a drum machine: https://www.youtube.com/watch?v=bZg1LFFhqms

He has a few good vids about drums, just look up “reaper Mania drums” on YouTube.