We now need to create 33 recessed holes in the base to accommodate the marbles, to achieve this we can start by creating a vertical centre line and a horizontal centre line @ approx 150mm, on top of the vertical line i created an 11mm circle and space them out approx 20mm left and right we now have 3 circles at the top of the base.
We can now go into the Solid function and select Pattern then Rectangular pattern, highlight the 3 circles and start dragging them down, the default number will be 3, change this to 6 and drag down the base till they are uniform, we then use the same process and select the 3 mid point circles on the left and drag out creating 2 more copies, same on the right hand side.
We should now have 33 circles, we now need to recess the holes.
I had to get my thinking cap on here, I could have extruded the circles to say -1mm and then filleted but the marbles would still move, a concave recess would be so much better.
This next part of the design ended up being a bit of a chore and there is probably a better way but I am on a learning curve as well so here is how I did it.
Selecting the solid function, I clicked on the Sphere tab and then highlighted each centre circle and used the Sphere to cut the recess function, I did this for each individual circle another 32 times as it wouldn’t let me do a rectangular pattern, once I got into a pattern it went seamlessly and the end result was 33 concave holes.
To finish the design I made a fillet around the edge, I will be using a 6mm ball end router bit for cnc operations and this will fillet the edge nicely, or you could always router the edges of the base.
Onto the cutting part of this Instructable.