13.36 Joining MIDI Items
You can join a number of MIDI items together, perhaps to create one loop enabled item, or to be able to edit them as one item, or to be able to export them as a single MIDI file.
Kind: concept (user-guide-section) Chapter: 13 Working with MIDI Items Source: REAPER User Guide v7.70
You can join a number of MIDI items together, perhaps to create one loop enabled item, or to be able to edit them as one item, or to be able to export them as a single MIDI file.

You can select all of the items (right-click and drag is often the easiest way to do this) and glue them together: right-click anywhere on the selection and choose Glue items from the context menu.

You can then double-click on the glued item to open the MIDI Editor, from where you can export it as a single MIDI file (File, Export to new MIDI file …).