I am struggling to send midi from a vst instrument to renoises own sampler. I can easily direct it to the plugin instruments, but I cannot find a way to direct it to the sampler. Is this possible without external midi tooling?
I am not sure if I understand what exactly you are trying to do, but I get the feeling that you want the vst to control a native Renoise instrument. Is this right?
Not really familiar with complex midi setups but to my understanding Renoise always uses the midi in to control the currently selected instrument. So presumably if the vst can be routed to Renoise’s midi input it would then play the selected instrument. I would guess that to control multiple instruments, each instrument might need a separate opened Renoise instance.
You can just use the dropdown in the Plugin tab (midi routing).
When you hold down a key It will play the sample based intrument with the pattern from the vst.
You can record the audio; does not seem possible to record the notes from the vst into the
pattern editor though, not without additional tools it seems.
Played around with this a bit and this is how I was able to route things so that it seems to work.
The left instance of Renoise has a VST instrument being controlled by a midi keyboard, it in turn is controlling the midi-in device from the other Renoise instance on the right which uses the midi-in as the primary input for its midi. It will record the notes into the pattern. So if the VST is running an arpeggiator all the arpeggiated notes should be recorded by the second Renoise instance.
Does not seem to be possible with just one instance of Renoise open…
Thats a shame… I was hoping to use VCV rack to sequence the looper, but if it requires multiple instances of renoise, I may aswell just use standalone VCV rack to feed midi in, rather than the VST version.
Perhaps something like this could be used to work around the issue 
Yes, Im aware of loopmidi as a solution, since that would also be required for running vcv rack externally, which is what I am probably going to end up doing.
Ofcourse you can send midi from a vst inside renoise to a renoise instrument
Load your midi generating vst , go to plugin tab and choose midi to ( right under the tabe render to samples °
Choose your destination , inthe example you clearly see a renoise instrument as destination
Had to try this out myself too 
Yeah, so it does work pretty well but as mentioned by Jek the generated notes can not be recored within just one Renoise instance. I’m not sure if that was an actual requirement here, but I suppose with generators that put out random stuff each performance will be different so it might be nice to record the notes.