Why not use CNC machining for beams, I want to designers and manufacturers are considering cost, because the CNC machining for manufacturers is not very complicated things, but we must pay more money when buying the kit, the designer can consider his manufacturing costs in the development of the kit and the purchase cost of the buyer, will find a balance between the two. Like now in the market for sale of ship model, each of the model simplified, with real ship is little different, of course you can also buy these models after when making kit for a lot of transformation, makes the model more real. And CNC machining the crossbar slot, there will be a disadvantage, that is the problem, because CNC cutting tool in machining 90 degree angles at the bottom of the right Angle will be a semicircle is linked together, the model built need to repair each slot.
Here again, all people are welcome to your comments here, even contrary opinions, and put forward your question, I will into the best effort to answer, also welcome to have know answers to all the people to help me answer, thank you