Train the third man combination using the simplest possible setup. One spare player forces continuous movement, and the fixed short-long alternation means every player passes both lengths in turn.
Lay three markers in a triangle about eleven metres a side. Four players. The rhythm is a short set of four or five metres followed by a long pass of around ten to the next station. Because there are four players and three markers, one is always travelling to the station he is about to receive at. Nobody plays two long passes in a row. Two touch, then one touch on the sets, and reverse direction after a few minutes.
A passing triangle with three players and three markers is the most common shape in football coaching and one of the least demanding. Everybody has a home, everybody stays on it, and the ball goes round. It warms players up and teaches almost nothing.
Adding a fourth player to the same three markers changes it completely at no setup cost. Now somebody is always without a station, which means somebody is always travelling, and the pattern only continues if that player arrives at the right place at the right time. Nobody can stand still, because standing still leaves a station empty and the sequence dies.
The short-long alternation on top of that is what makes it a third man exercise rather than just a rotation. The four metre set is a preparation pass, and the ten metre ball that follows it goes to the player who has been arriving. He was not involved in the set at all, which is exactly the position a third man occupies in a real attacking move.
The simplicity is a genuine virtue. Three markers, four players, no mannequins or poles, in an area eleven metres a side. It fits into any corner of a pitch, it works with the numbers a coach is often left with, and the difficulty comes from the structure rather than from equipment, which means it does not degrade when the cones run out.
Save it to your private drills, then change the animation, adjust positions, swap equipment, or drop it into a session block. Or start from a blank pitch and build your own.