Jumping spider enclosures
Tall, ventilated, and openable from the front. Everything else is decoration.
A jumping spider uses vertical space. It hunts by walking up, looking down and jumping, so a tall enclosure with a modest footprint suits it far better than a wide one with the same volume. For an adult, something in the region of 15cm square and 20 to 30cm tall is generous. Much bigger and feeders get lost in it; much smaller and the animal has nowhere to jump to.
Ventilation matters more than size. Cross-ventilation — mesh or drilled holes on two opposing surfaces rather than one — is what lets the enclosure dry between mistings, and drying between mistings is the whole of humidity management for this species. A sealed acrylic box with a few pinholes in the lid holds damp air at the bottom where the spider is.
Open from the front, not the top. This is the one piece of setup advice worth being firm about: a jumping spider builds its hammock in the highest corner it can find, which in a top-opening enclosure is the lid. Every time you open it you tear the animal’s nest, and if it is mid-moult in there, you may do far worse than that. A front-opening door makes routine maintenance a non-event.
Inside, it needs something to climb, something to anchor silk to and one dark corner to retreat into. A piece of cork bark, a couple of artificial leaves and a length of branch is a complete furnishing list. Substrate is there to hold a little moisture and catch mess — coconut fibre a couple of centimetres deep is plenty. A bioactive setup is a pleasant hobby in its own right and is not something the spider requires.
Skip anything with standing water. A dish deep enough to drink from is a dish deep enough to drown in, and the spider will drink from the wall instead.