Herbal sleeping tablets - extract of valerian root to be specific.
This has the property of beings long range attractant (like oats) but a short range repellent. Thus meant the slime drew the tightest possible shape around the points.
This might be a way to model circular transport routes like buses, or logistic networks or the last thing I used convex hills for - reducing several thousand loadcases to to the worst ones for a pile design.