[smurfyou]

You should be able to fashion a sliding shelf for one. I'd feel better doing one with a 61 rather than 88 key simply for weight reasons. The Halo is not flat underneath and there's the cable tray to watch out for. But with a few pieces of wood I don't imagine it would be too difficult. There are probably some diy guides online. Just don't skimp on the rails, get a heavy duty set.

I've seen others have a separate stand that slides out but I haven't tried that. Just a standalone shelf on legs. Might be an option if you don't want to modify the desk. I don't know how they glide, maybe just some felt feet?