Warm the body up while training the habit that matters most in possession: pass and move. Take the technique out and the decision is all that is left, so players learn to create an angle rather than stand and watch.
Mark a 35x25m grid and split into two teams. The ball is thrown and caught only. You may not run while holding it, and you may not hold it for more than three seconds. Ten consecutive passes is a point. An incomplete pass, a dropped catch, or a ball on the floor turns it over. Play four or five minutes, then move straight into a football version of the same game so the habit carries over. Keep the grid generous at first, and shrink it once players are finding each other easily.
Take the feet out of it and you find out who actually understands space. When a player cannot get free in a normal possession game, there are two possible explanations and they demand opposite responses: either he does not know where to go, or he knows and cannot control the ball well enough to get there in time. Handball removes the second explanation entirely. Everybody can catch and throw, so whatever movement problem remains is a reading problem.
That diagnostic value is the real reason to run this rather than the usual justification about fun. Watch the players who are constantly available with their hands and compare them with the list you would have written from watching them with their feet. The names differ more than most coaches expect, and the difference tells you which players need technical work and which need to be taught where to stand.
Within the game, the support angles are what to coach. A receiver directly behind the ball carrier is easy to defend, and one who moves to a diagonal is not. That geometry is identical in football and much easier to see when nobody is chasing a loose ball.
Movement after the pass is the other transferable habit. A thrower who stands still has removed himself from the game, and the consequence is immediate and obvious in a way it is not with feet.
Keep it genuinely short. It warms the group up and produces information, and there is a point at which a handball game stops informing anybody about football and becomes handball.
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.