Inverted Round is similar to Roundmaille, but the rings are flipped up in IR, rather than alternating up/down as in Roundmaille. Inverted Round by itself isn't terribly stable, and the cages can collapse in, leading to a messy appearance. The cages can have rings put inside them for stability and aesthetics, giving Captive Inverted Round.
Inverted Round can be made with rings around 4.2 and up. 20awg 1/8", 18swg 3/16" and 16swg 1/4" rings will work. Raising the inner diameter will give a larger, looser chain.
Metric sizes - approximately 0.8mm wire/3mm ID; 1.2mm wire/4.8mm ID; 1.5mm wire/6.4mm ID.
All rings are steel.
Step 2: Close 2 rings and put them on an open ring. Connect the open ring to 2 of the closed rings from the previous step. They should now make a 2-1-2-1-2 chain.
Step 3: Bring the two ends around and connect them with a single ring. They should now make a loop, with the horizontal rings in two tiers.
Step 4: Flip the bottom-tier rings down, and the top-tier rings up so it makes a tube shape. You now have 3 'cages' that form the basic units of IR. Now you'll just make more cages.
Note: Right now it's not very stable, so try to keep it bewteen your fingers for the next few steps. You can put an extra ring, a piece of wire or a twisty tie through the bottom cage to keep it in place.
Step 5: Pass an open ring though two adjacent rings in the top cage.
Step 6: Pass an open ring through two more adjacent rings in the top cage. Make sure it doesn't go through the ring you added in the previous step.
Step 7: Pass an open ring through the remaining two rings. Again, make sure this ring doesn't go through either of the rings you added in the two previous steps. This completes the next cage.
Step 8: Repeat Step 5 with two adjacent rings from the top-most cage.
Step 9: And keep going with the next ring, making sure not to pass the ring through the ring you just added.
Step 10: And so on to complete the next cage.
Step 11: Repeat Steps 8-10 until the chain is the desired length.