  We show that non-perturbative fixed points of the exact renormalization
group, their perturbations and corresponding massive field theories can all be
determined directly in the continuum -- without using bare actions or any
tuning procedure. As an example, we estimate the universal couplings of the
non-perturbative three-dimensional one-component massive scalar field theory in
the Ising model universality class, by using a derivative expansion (and no
other approximation). These are compared to the recent results from other
methods. At order derivative-squared approximation, the four-point coupling at
zero momentum is better determined by other methods, but factoring this out
appropriately, all our other results are in very close agreement with the most
powerful of these methods. In addition we provide for the first time, estimates
of the n-point couplings at zero momentum, with n=12,14, and the order
momentum-squared parts with n=2 ... 10.
