If you want an effect to be constant, set the level and
Price accordingly. For instance, let's say your group is 9th level and you want to give them an item themed around allowing the entire party to
fly. The 3rd-level augmentation
ultralight wings provide a
fly Speed for one character, and a 5th-rank casting of the
wild bond focus spell gives most parties a fly Speed, lasts a minute, and can be cast multiple times per day using the
Refocus activity, so it can cover flight by 9th level. To keep it simpler, you decide to create a 9th-level magic item that creates a swell of primal energy causing allies around you to grow wings and gain a fly Speed for 24 hours. Remember, some effects were never meant to be constant and could warp your game.