Waist bags for tools

Waist bag

— belt bag; can be equipped with its own waist belt or hung on a separate belt. Also note that an open bag (without a flap closure) is sometimes referred to as a "holster".

Anyway, such devices are great for situations where you need to constantly move around and at the same time always have certain tools at hand. Vests have similar specifics (see the relevant paragraph); they are more capacious, but the belt is easier to choose in size.