Ultra high precision and accuracy printing I work in a teaching hospital and we have a research project we're interested in pursuing.  We'd like to 3D Print tubes we'd implant into rats to help with nerve regeneration.  We're interested in the shape of the tubes right now, more so than what material it is or whether it's biocompatible etc..   

So this question isn't necessarily about what type of plastic or whatever we should print in.  My question is more so:


  We'd like to print a tube that's 1&nbsp;mm in diameter, about 1&nbsp;cm
  long and has as many micro "tubes" crammed through it as possible,
  something like this:
  
  


I currently have a Stratasys j750 in my lab, a UPrint Se and a Prusa i3 Mk3s.  They all work well but for the detail I'm looking for, come up a bit short.  They have advertised accuracies of 14 microns (well, the j750) but thats just in the z direction, x and y are more like 200.  If I went to get PRECISE, what technology should I look into?
This is an interesting question. A good thing to note when we start talking about SLA and other jewelry grade 3d printing, that you will have to factor in the materials toxicity when we start talking about medical applications. You can also look into DLP 3d printers but they will not have as good quality. 

What can help you right now is these SLA printers I see that form 3 has 25 microns, with a laser dot of 85. Well within your tolerances. Just make sure to get dental grade or medical grade resin. 

Note that if there are bends, then you will have issues with SLA printing, depending how steep the angles are.

There are other technologies, such as metal 3d printing or SLS printing, that will likely be out of your price range such as the HP Metal Jet that can do 21 -xy by 50 -z microns. Or binder based 3d printing which will have the best internal geometry, as powder will act as support, and is easily removed. 

There are many specifically in the bio printing area that might be what you are looking for as well, this is more an alternative. You can look into what the researchers at Penn has been doing, where they have been using Sugar to create vascular networks. As far as I know they do not sell it as a product at this time. Here is more information about scaling vascular networks 

See here for more information about other printing technologies