Remember to account for the volume of the confetti bits when calculating the recipe size. A 5 pound mold will NOT hold a 5 pound batch of soap once you add 1 pound of confetti.
If using a small to moderate amount of confetti, blend to a slightly thicker trace and stir confetti into batter before pouring into mold. so the bits don't just sink to the bottom.
If using mostly confetti, place confetti into mold, blend soap to very light trace and pour into mold. so the new soap flows to surround the bits.I saw a beautiful bar that looked like it was poured in layers but it was made with colored unscented confetti placed in the mold in layers, then thin highly scented uncolored soap poured to bind it together.