It's hard to pick the best wording for things like this.

By now, the sweat beads decorated his forehead so liberally that they resembled liquid wampum.

By now, the sweat beaded his brow so thickly it resembled liquid wampum.

By now, the sweat beads decorated his forehead so liberally that they resembled liquid macramé.

By now, the sweat beads decorated his forehead so liberally that they resembled that one type of lanyard I used to make tons of during craft time at camp.