Donald Osselaer created the Ultraburr, together with the Xenon without the help of a computer. Burrtools was only used to add colours and ensure that the solution was unique.
I first thought out the "ideal combination" being 1-2-1-3-1-2-1-4-1-2-1-3-1-2-1-5-1-2-1-... etc. and then I tried to make a puzzle that forced this solution. I find this type of puzzle to be much more pleasant compared to purely computer random based designs. Donald Osselaer.
In this quote, each number given by Donald represent a different piece. The sequence gives the order in which the pieces should be moved. It is nothing else than the sequence of the Tower Of Hanoi if the discs are numbered from the smallest to the largest.
The conception of the Ultraburr is roughly based on the same logic, but fortunately, the puzzle is much more complex than the Tower Of Hanoi.
The level of the puzzle is 18.104.22.168.22.214.171.124.3.4.3 according to Burrtools. However, several rotations allow to reduce the number of moves to 126.96.36.199.188.8.131.52.5. Some of these rotations should be geometrically impossible, but the margin is so small that they can be performed without any problem on a real-world model.