Use one ball. Play for c. 5 minutes, or first to 10 or whatever. Round the bases Set up with a fungo hitter and a shagger at home, a first base and a line of fielders next to third. The first fielder takes position as third baseman. The fungo hitter hits a grounder to them, they field it, throw to first and move to short-stop, repeat at short stop, then move to second.
First base rolls each caught ball towards home where the shagger tidies up.
If there are enough people use a back up at first. Pivot Plays Set up with two lines of fielders, one of second basemen and one of shortstops. Also need a fungo hitter, a shagger and a first baseman. The fungo hitter hits balls in the general direction of second base. The basemen and shortstops practice working the double plays.