I have a weber mass and its great... it has no issue with 2 ohm loads. Well worth the 200 bucks I paid for it. Its great if you want to back down the volume a few notches. No attenuator ive ever heard sounds great taking an amp on 10 down to coversation levels. If you need 8 on your amp to sound like 5... this is the way to go.
https://taweber.powweb.com/weber/mass.htm
as far as plans go sorry I dont have or know of any.