This is another popular siteswap Mills Mess pattern. This trick combines the arm movements of Mills Mess & the throws of 531.
Technically there are three different versions of 531 mess, they can be thought of as 531, 315 & 153. This tutorial covers the easiest version.
Start by practising the '31' of the pattern, which is an exchange of two balls. Hold one ball in each hand & cross your arms over. Begin with the hand that is on top. Throw a low back toss, no higher than your chin, from one side of the body to the other. Uncross your arms in the same movement, then immediately recross your arms the other way around. As the hand that threw first begins to pass under the other one, turn the hand holding the ball over from palm up to palm down, so that the ball drops straight into the empty hand. Catch the first ball with the arm that goes on top.
Now do the same the other way. Work on getting a nice smooth uncross & recross. The first throw & the uncrossing of the arms should be a single movement. When you start & finish the move make sure that your arms are definitely crossed over, it is easy to fall into the habit of ending up with the hands side by side & the arms crossed at the wrist. Aim to start & finish with each ball level with the opposite elbow. Make the first throw go all the way to the other side.
Practise this move to death until you can do it smoothly & quickly starting from left & right arms on top. Try to get to the point where you can do the move without directly looking at the balls too.
Now pick up your third ball & juggle a standard Mills Mess. Focus on the Under arm throw for a bit. Keep juggling but when it comes round to making the under arm throw, throw it really high. If you are practising indoors, throw it up to the ceiling. While the high throw is in the air, just wait with your arms crossed over & with one ball in each hand, don't carry on making all throws to ceiling level. This exercise just gets you used to making high under arm throws. It can be quite difficult to get the height because there is an arm in the way of your scooping action. To compensate just scoop lower & bring your hand up in a straighter line than normal. Also use your wrist & fingers to get that little extra lift into the throw. Keep practising until you can consistently throw a ball under your arm to ceiling height without putting in any noticeable extra effort.
Now for the full trick, throw a high under arm throw, but instead of throwing it straight up, throw it across so that it will land on the opposite side of the pattern. Then throw the back toss as you uncross your arms & pass the third ball as you recross them. Throw the passed ball straight up under the arm, catch the high throw & carry on juggling Mills Mess as normal. That was one side of 531 Mess. Practise throwing one round of 531 leading from alternate hands & falling back into a normal Mills Mess pattern. Keep your attention on the high throw as it peaks; watch the low throw in your peripheral vision.
Either gradually reduce the number of standard Mills Mess throws you put in until every under arm throw is a high throw or go for the full pattern straight away. To help keep track of the pattern it may be useful to know that the high throw is the 5 the low throw is the 3 & the pass is the 1. The 3s are always the same ball every time while the other two balls are thrown as 5s & 1s alternately.
For a challenge Penguin Catch the 3.