first and foremost, what species of dart are you planning on keeping? what size enclosure? keep in mind that some species are strictly terrestrial and require as much floor space as they can get, while others are partly arboreal and you can get away with having a larger water feature. keep in mind that things get real tight, real fast as you start building.it really comes down to what the frogs need, first and foremost, and what you want to see second

choose a species first, then design a tank for them. believe me when i say this, it will save you a LOT of headaches in the long run