Slimes aren't fast, small mazes (10cm) take around 2 days to run, big ones can take a week.
We like paper for growing up slime moulds to a decent size but for mazes you really need to use agar - slimes often wander off paper and start exploring the bottom of their petri dish which isn't very helpful.
You can get agar very cheaply as vegan 'gelatin' (do not use real gelatin, it's made of protein, slimes digest it) - you need plain unsweetened, unflavoured agar. As it's plain agar it doesn't need to be sterilised - there's no nutrients in it for other things to grow. 2% agar works well for cutting out - that's 2g agar in 100ml of water.
Agar is easy to cut out, cocktail sticks work well and won't scratch the container. Remember the slime will be on the agar - the walls are the gaps.
About a teaspoon of slimy yellow oats is a good starter, the slime will explore by spreading itself out looking at multiple paths at once. Any lanes where our slime doesn't find food it'll quickly give up on and leave a trail of mucous - a chemical memory that tells it where it's already been.
Food preference is quick to set up and can be finished in a day. It's a great way to demonstrate chemotaxis. Slime moulds don't like very acid or alkaline environments, they avoid salt and poisons like caffeine but they also need food to survive. By tasting the chemicals dissolving out of the food into water in the surrounding area slimes can weigh up the pros and cons of a piece of food, does the prospect of valuable carbohydrate and protein outweigh the risk of getting exposed to acid and salt on a crisp? (If you try this, please tell us about it!).
Paper works really well for this. Try to put the all the food the same distance away from the slime, the closer it is, the faster you'll see results - but you might also miss something the slime will do if it's got more time to 'think'.
Slime mould food choice
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