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Any mechanism for generating a neutrino beam starts with a way to generate neutrinos, and there is only one underlying means right now: weak decay (including beta decay in radioactive nuclides).

These are three body processes (at tree level) which means that they generate a non-trivial distribution of energies for the products. Being light the neutrino(s) always have a energy distribution that goes to a large fraction of energy available from the decay on one end and to zero on the other. So you can get a few low energy neutrinos just by collecting a large sample of things that decay by weak processes.

But that's not a beam. To make a beam, you have to control the direction. 

Conventional beams rely on Lorentz focussing meaning that the progenitors must have a large Lorentz factor, so those beams are necessarily significantly relativistic. You can't make your low energy beam that way.

All is not (yet) lost. Neutrinos are fermions, so they have spin. And they have the unusual property that all are left-handed and anti-neutrinos are all right-handed (in the standard model which we know is wrong in some ways about neutrinos; the jury is still out on this being a actual unbreakable rule or just very strong). 

If we had a low energy decay where the mother had a non-trivial angular momentum and could prepare the mother sample in a highly polarized state we could generate direction preference for the neutrino. 

From this point on I'm just guessing, but I would expect that this is not a strong preference: more like the simplest directional antennas (the energy goes into one half of space) then something that you would normally term a "beam".

So that's something, but not great. It's not very focussed and it won't be mono-energetic.

And it gets worse. Due to weak universality, decays with a small amount of energy available (which we want to keep the neutrino energies low) will have a longer half-life. So we need a bigger sample and will have a harder time keeping it polarized.

Will you settle for "kinda a beam and very low intensity"?