  The design and implementation of large sets of spatially-extended,
gauge-invariant operators for use in determining the spectrum of baryons in
lattice QCD computations are described. Group-theoretical projections onto the
irreducible representations of the symmetry group of a cubic spatial lattice
are used in all isospin channels. The operators are constructed to maximize
overlaps with the low-lying states of interest, while minimizing the number of
sources needed in computing the required quark propagators. Issues related to
the identification of the spin quantum numbers of the states in the continuum
limit are addressed.
