hi michael

why this happen

i make this
https://imgur.com/3WaeNXF

and connect it with network this look like this

https://imgur.com/MU33Yl1

and i mark all with ctrl + a and click on OFFSIET and click on SHELL, and i give thnickness and i put 0.07 direction is normal

when i export it .obj and open it in 3d coat see what happen inside is transparent, how to fix it.
https://imgur.com/u77Id7X outside

https://imgur.com/X3fZfEl inside

here is 3dm file
https://files.fm/u/xzmfe54s

Hi 4rw1n, unfortunately the Shell function in the geometry library that MoI uses does not work well with a case like this with multiple surfaces meeting at different angles. For thickening an open surface it will only work on a single surface or with multiple surfaces that are smooth to each other or meet at a 90 degree angle.

For thickening something like you have here it makes messed up results in corner areas.

So I'm sorry Shell just won't work for your case, you need to use some other method for constructing it.

- Michael

Hi 4rw1n, also on something like that it can work better to make a solid and then shell the solid rather than trying to thicken an open surface. With a solid shell the shelling mechanism gets to intersect extended surfaces with "side walls" which tends to work better. When you thicken an open surface it's a pretty different process which has more difficulties with surfaces all at different angles to each other.

I've attached a result of making your object into a solid and then shelling it. There was still an error in one spot where you had a thin pointy piece which I had to fix up manually.

Also I made all the main pieces using Construct > Planar rather than Network, that should also help with offsetting and shelling work since it will make trimmed analytic plane surfaces rather than general surfaces.

- Michael