In a 3-dimensional crystal, the electrons’ energy-momentum relationship is a hypersurface in (3+1)-dimensional space, so I can’t show you a good picture of it. However, I can show you the region in momentum space that the crystal’s electrons fill. Here's what the filled region looks like for some real metals.
These models were designed by Douglas Roaf, based on measurements by David Shoenberg.
Drag the cage around the filled region to rotate it.