Nonoise, the Ingress Audio Rollerblocks come in sets of three, each having a top and bottom cup. The provided 3/8" ball bearing is placed in the bottom cup, the top cup is placed on the ball, and the component on top of that, just as Symposium Acoustics RollerBlock Jr's. Using both cups makes for a slightly higher resonant frequency and more damping that using just the bottom cup (as with the Symposium original model). Barry recommends using only the bottom cup, with a hard smooth surfaced object (a stainless steel disc, for instance) on the bottom of the component, for the ball bearing to roll against. You are free to try them both ways, of course.
Ingress also offers a newer model Rollerblock, made from harder 7075 aluminum, and with a larger, shallower bowl, the bowl being machined as part of a 2" diameter sphere. The less steep walls of the bowl provides a lower resonant frequency and less damping (the ball rolls for a longer period of time) than the original model, and this model is sold in sets of three, intended to be used on the bottom only. The ball bearings are the same 3/8" diameter, and the set of three is $90 plus shipping. The aluminum of the bowl of the 7075 model is also more highly polished than that of 6061 aluminum original model, for less friction. The 7075 model provides more isolation than either of Symposium's models (as well as the Ingress 6061), a result of the bowl's dimensions.
Isolation in the vertical plane, if desired, needs to be dealt with separately. The cheap DIY method is an under-inflated inner tube on a piece of plywood, which works as well as any commercial product, including Townshend's original Seismic Sink, which was not cheap (and is no longer available new). You can even put a piece of ply across the front of the platform, to hide the inner tube, paint the whole thing black, and have the best isolation known to man, for only a few bucks.
Ingress also offers a newer model Rollerblock, made from harder 7075 aluminum, and with a larger, shallower bowl, the bowl being machined as part of a 2" diameter sphere. The less steep walls of the bowl provides a lower resonant frequency and less damping (the ball rolls for a longer period of time) than the original model, and this model is sold in sets of three, intended to be used on the bottom only. The ball bearings are the same 3/8" diameter, and the set of three is $90 plus shipping. The aluminum of the bowl of the 7075 model is also more highly polished than that of 6061 aluminum original model, for less friction. The 7075 model provides more isolation than either of Symposium's models (as well as the Ingress 6061), a result of the bowl's dimensions.
Isolation in the vertical plane, if desired, needs to be dealt with separately. The cheap DIY method is an under-inflated inner tube on a piece of plywood, which works as well as any commercial product, including Townshend's original Seismic Sink, which was not cheap (and is no longer available new). You can even put a piece of ply across the front of the platform, to hide the inner tube, paint the whole thing black, and have the best isolation known to man, for only a few bucks.