Is there an easy way to build one side of a character, rig it, then weightpaint it, and then mirror it? Weightpainting both sides of a character model seems a bit tedious and redundant if both sides behave the same way…
yes!
okay, theeth has covered this before, but I shall now
you make one half, and weight paint it and everything
duplicate [shift+d, not a linked duplicate] it
mirror it, flip the normals [yeah yeah]
then enter edit mode and rename the groups to the bones on that side
join with the original, remove the seam
voila