The Żłob Modular Attenumixer is a 4hp three channel summed passive attenuator. Each channel can be used independently or the sum out provides a mix of all three channels. Good for beginners with no experience. DIY kit $30.
The Żłob Modular MiniAtt is a 2hp dual passive attenuator with toggle/mute switches for each channel. The sum out provides a mix of both channels. Better for beginners with some experience. DIY kit $25.