My Challenge to Make a Marble Run Machine - A Tiny Step Forward

I made a little progress on a marble run machine yesterday. Although, it is still the beginning of the process.
The base board of the marble run machine is 600 mm x 1200 mm and quite big. Therefore, it was not easy to handle it. I bought the board at the local hardware shop. The board is not an accurate rectangle. Well, never mind.

I want to make a marble run machine that can change some parts. It is also convenient that I can replace a part partially in case it is broken. Therefore, I marked 2mm tiny depth holes on the board's surface using the CNC router. Those little holes will be indicators when I set each part.
I asked for help from Juno when I used the CNC router. It was because the board is big and cannot mark holes at once. This means I had to set the board twice. It was risky to move the board; I might have set the wrong position and made a mistake. Juno and I very carefully measured the position of the board. Thanks for being careful. We somehow managed to drill correctly. Now, the base is ready. However, this is just the beginning.

I have not decided on the whole design of the machine.
I have two chains. The longest one is 785 mm long, and the small one is 534 mm long. They occupy the space quite a lot. It is a bit difficult to think of the layout of the machine in the rest of the space.

I am going to display it on a wall, so it is good for making it as flat as possible. However, thinking of what I want to make, it would be thick by all means. The plan I had before I started making it is getting changed. I do not hesitate to take lots of time. Most importantly is making a fun marble run machine.

I want to make the marble run machine that friends who visit my house will enjoy seeing.