Well, it takes a while, but DIY Instrumentals are possible with only one file.
Heres my theory (worked every once in a while):
1. Import Audio
2. Split Stereo to Mono
3. Invert one of them.
4. Mix and Render both tracks together.
---This is technically an instrumental itself, but all it does is remove centered audio.
5. If there are high-pitched random things, find out the pitch of them, then use the "Vocal Remover (for center panned vocals)" and set the spectrum to 0 as minimum, and just below whatever the pitch of the noises is.
---This will remove the high pitched things, as long as you set it to "Retain Frequency Band" mode.
- - -If you know the pitch range of the vocals, use the Vocal Remover, and do "Remove Frequency Band" and enter the lower pitch and higher pitch of the vocals so that it only removes them, and and centered instruments in that range.
It's nearly the same as making DIY Stems.
Which is harder.