There are a few things that prevent a permanent or fixed bonsai bench being installed: 1. our property is rented 2. The courtyard is small and paved. I used to utilise the cinder block and sleeper method, but have since found this solution much more practical especially for a small area, stable at a good viewing height, and it can be pulled apart in about 15 mins if required. I added a water retrieval tray to not only collect water runoff, but also the ferts/tonics that would other wise go to waste
Components include: black heavy duty storage rack shelving system http://www.bunnings.com.au/our-range/st ... y-shelving; sleepers; 2x4 timber lengths (cross supports holding the timber above the shelving racks); custom made metal water collection/retrieval tray complete with large metal BBQ squewer in hole to draw and guide water into the bucket below.
The shelving racks are powder coated and have been erected outside for more than 18 months with no evidence of rust so far
, just spider webs 
Hope this helps or inspires other creative solutions
) certainly over engineered, but the benches don't move, with more cross supports you could use decking wood such as merbu as an alternative. 
or even the mesh shelving that goes with the system, but I do like residual moisture the sleepers provide under the pots in the summer...
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