Size and scale is not mentioned in the RASA model. The assumption is that an ultimate machine of this nature would handle matter and energy in chunks small enough to handle any task, so everything from extremely large masses to individual atoms must be considered, at least in theory.
For the practical task of making machines that approximate this ultimate idea, one of the first questions a builder would need to answer is: “How big will it be?” The standard block size will drive all other design considerations.
This is not a one size fits all scenario. Clearly, large amounts of bulk material is best handled by large containers, and fine scale work needs small components. It makes sense to make a range of device sizes.
One way of picking a scale would be a factor system, where each device sizes are simple multiples of each other. Each machine type being half or twice the size of the the next size would make a certain amount of sense.
While not being exact size multiples, a multiple of carrying capacity can be used instead. Since RASA units are made to carry anything, it seems handy to have the ability to carry smaller versions in much the same way as ferries carry vehicles. Following a cubic stacking arrangement, one unit could be built to carry 1, 8, 27, 64… etc. smaller units inside.
Ease of construction is also important, especially for prototypes and early models. Choosing a size too large leads to working with heavy machinery and all the difficulty and expense that goes with it. Similarly, choosing a size too small brings problems and expenses of miniaturization. There exists a “sweet spot” of scale, where most problems are easier and cheaper to work out. For early designs at least, it’s important not to stray far away from this ideal scale range. After all, a trip to the local hardware and electronics store is easier than working with cranes or microscopes.
Integration is also very important when choosing a scale. We want these machines to do a lot, so having them compatible with what we already have is vital. Ideas include RASA modules built to accommodate standard forklift pallets and shipping containers or to easily hold a standing person. On the smaller side, a system that is optimised to handle a banker’s box or a reasonably sized grocery bag can be very useful. Smaller yet, something made to handle postal mail could be useful. Even smaller sizes could have potential uses, as it’s hard to imagine everything a self-building system could do.
With all this choice, it’s easy to see very many incompatible standards come up. I think that for a while it will be a matter of trial and error as to what will prevail. My personal choice for my prototype involves taking off the shelf hobby parts, and building the largest sized units I can that won’t overly tax the cheap motors and batteries I use. I plan to post updates as this system develops.
The far future of this technology will have very interesting issues of scaling to consider. Once we have machines that can make copies of themselves, the idea of slightly larger or smaller copies comes up. The result can be similar machines at sizes we can find hard to imagine right now. On one hand, reconfigurable buildings are a possibility, and on the other, moving into truly useful micro and nano machinery is possible. This is one of the reasons I think that this simple technology can be the gateway towards ideas that have only been previously thought of in science fiction.