When you say "make your own module from a python module", what do you actually mean? Generate Nim code based on python code? If so the answer is no.
If you want to write a Nim module that calls some python module the answer is yes. If you give a more concrete example of what you would like to do, I can give a clearer answer.
That is as simple as
import nimpy
let np = pyImport("numpy")
let a = np.linspace(0, 10, 1000)
let f = np.sin(a)
echo f
It all just magically works.
See also here: https://github.com/yglukhov/nimpy/blob/master/tests/tpyfromnim.nim#L61-L82
and possibly in many other places. From the top of my head I don't have any good examples.
The library error occurs because Nimpy cannot find libpython. This means that either libpython.so (assuming Linux) is missing or not in LD_LIBRARY_PATH (again, assuming Linux). If it's not installed, you can usually run sudo apt-get install libpython3-dev (or whatever package manager you use) if libpython is not installed. If it's installed, then make sure the location of the library is in LD_LIBRARY_PATH
Could be also that you're running some odd version of libpython that is not supported by Nimpy (very unlikely).