Cut a piece of weed-smothering membrane to about 1m², allowing a little extra at the edges to tuck around the chicken wire. Use it to line the base of the heap to stop roots and weeds invading your leaf mould and rendering it unusable.
Depending on the width of your chicken wire, cut four tree stakes and hammer them into the ground about 1m apart, using a rubber mallet.
Cut a length of galvanised or coated chicken wire to go around the four posts, allowing some overlap, and secure it with wire or twine.
Your cage is now ready. If you chop up the leaves first to reduce their volume, you'll be able to cram more in. They will shrink down by about two-thirds once they start to rot and should be ready in a year or two.