I got myself one of CoinTaker's Red Tremor shaker motor for my BDK and man that thing was making the entire house rattle like a jackhammer (although partly due to Australia's poor construction quality too I must admit).
Anyway it's a shame the strength can't really be adjusted (you can try and play with the weights but that didn't do it for me) so I just added a $1 / 3 Ohms / 20 Watts resistor in series and Bob's your uncle, perfect intensity for me.
(5 Ohms is too soft. Haven't tried 2 Ohms but I'm guessing that's what somebody with a more solid house would want to try.)
Just letting you know.