One of my absolute favorite things I like about Reaper over Sonar is batch rendering, which Sonar lacks. Some DAWs can do it, but not all. Any kind of audio based job where you need to export a bunch of files, is a job for batch rendering. So it's an absolute necessity for sound design and album mastering, among other things.
The first way is to use the Render dialogue box. Here's an example. This is better for rendering across tracks than rendering multiple items within a single track. Remember to select Stems (selected tracks) in the top box.
Note: this gif example would not properly create renders of the items only, it would render the entire project length. To make it work correctly in this example, you would first create regions for each item, then set the Render Bounds to region.
For item-based rendering you want to use the Batch file/item converter. Here it is in action.
So yeah, batch rendering, good times.