Thanks @tomlee! This is what I did (the pipe) for the prongs in center of the model (the blue ones).

And if even if I do boolean union for yellow and pink (or as a pipe) - it won’t always boolean union with the blue stone settings.

Since this is only my second model for wax ever, and the first one with the prongs, it took me a lot of figuring out - how long prongs should be… This is why I made them in 2 separate ways - to change the height easily.

After I will get it printed in wax and then made to a final product - I will see if the prongs are fine and next time will do the in pipe function.

So here what I did at the end -

**(I WILL BURN IN HELL FOR PERFECTIONISTS)**

- I
**x** and **y** scaled the pink bottom of the prong to **1.01**

.

- Then I was able to boolean union yellow and pink parts together. And also boolean union them to the bezels.
- Except 2 prongs which was not willing to join the bezel settings. So I added a small cube to add some more “meat” to the prong.

I the link above by @Helvetosaur - (which I will read more in details after I will have a more clue on the topic, otherwise it’s pretty much Chinese) I saw this paragraph. As I understand is the fail to make a boolean union.

"

Known Rhino limitations:

Coincident seams – all objects have

seams, sometimes when the seams on two objects are at exactly the same

place, Rhino will have trouble with the intersection. Solution – either

try to move the seam, or try moving one object just a tiny, tiny bit

(if you can without making your model inaccurate). Or try to do the

operation “manually”.

Coplanar faces – if two faces of an

object are on the same plane, Rhino may not be able to calculate the

intersection. This is a fairly common occurrence, try to avoid building

your model this way if you can. Solution – as above, you may move the

object slightly if possible, if not, you may have to do this operation

“manually”.

Nearly tangent surfaces – like the

intersection of two equal diameter pipes at an angle. The intersection

often fails at the point where the surfaces are tangent. There is no

easy fix currently for this problem.

"

So I believe I sinned on all these 3 points.

But I will burn in perfectionists hell anyway… Sigh…

Thanks everyone for the help!