Thank you both so much!!! Finally made it through, my circular arch! Couldn't be any happier.
With Profile Builder 1 Free edition, I don't have 'stamp' though I use 'Build' to create the 'Crown' profile, had a few adjustments - scale, rotate, copy the face, then FollowMe on selected path.

Or I may need to buy PB2 as it may be very helpful

I JointPushed it after exploding it, looks nicer?

Thank you so much Pilou!!Would you help me to try please?
I exploded it and did the scale then but it still wouldn't make the proper look.

My Arch.skp

Just tried to scale it up but it doesn't look good enough

I'm trying to make circular arches while in the tutorial I noticed it's the plug-in Profile Builder which seems very powerful however the free version I downloaded from our plug-in store doesn't have a dimension box that I can put in like 1.5m to create some realistic thickness for my arch. Is there any way to achieve this without having to purchase PB2? Can the JointPush plugin do the trick by group push the selected surfaces maybe??

My space truss is done! Only it's black tube, instead of white... Shall I do Reverse Face before doing everything else or something? )) But it's fun, at least some progress.

Thank you so much! I appreciate very much of your specific answer! Just solved this problem and moving forward, turned out it was the five groups that I didn't make enough. You were quite right, I didn't make Group 2 and 4! Heaps of thanks!!
BTW, is there any courses that you recommend me to take? I want to learn Sketchup modeling for a building with curved surfaces and maybe export to Unreal Engine for visualization. Are there any good training courses online or even maybe some designer degree that I can sign up for? I'd like to skip the basics cuz I've got them pretty much covered from learning here and youtube tutorials.

@pilou said:

The lttle cube with a shadow is not a Plugin!
It'a native function of the Tools Bar Shadows of SketchUp for enable / Disable Shadows
(from Location & Month / Day hours)
Flowify can work with or without Shadows!

Better if you post your SKP file (save as format "V 6") for a more large audience!
Put also the adress of the video!

From your alert message seems it's the "2 lines connection" who are missing!

Here the concept : make the groups like this
Group 1 = surface (Whitout hole) can be anything but "four sides"
Group 2 = (2 straight lines)
Group 3 = entiere wall (whithout hole)
Group 4 = G1 + G2 + G3
Group 5 = flat window (or any volume) not obliged to be pasted to the surface!

You select all
Call Flowify
"Projected window" is drawn (or any 3D volume)

Here 2 examples : with a flat window (on the right, with a simple box on the left up corner)

This are surfaces 4 sides fine working with Flowify!
[attachment=1:25w7wy1k]<!-- ia1 -->surfaces_4sides.jpg<!-- ia1 -->[/attachment:25w7wy1k]

This surface will not work with Flowify!
[attachment=0:25w7wy1k]<!-- ia0 -->surface_4sides1.jpg<!-- ia0 -->[/attachment:25w7wy1k]

I was learning from a youtube tutorial about making a space truss and was exactly following until I couldn't perform Flowify, and I noticed that in the tutorial the guy click on this (little square with a shadow) before clicking on Flowify, does it make a difference? What's this plug-in then and why isn't my flowify working? Please help. Thanks.

What I downloaded was only a .php file, not .rbz as normal plug-ins are.
Please help.I got 'pluginserv_joomla.php', did I do anything wrong??

@box said:

The Arrow keys will lock the different axes.

Nice way to keep it on blue axis, but not easy to lock the arrow, I need more practice.
Appreciate your answer.

@pilou said:

Draw a face where you want have the plane for the Curve!
Make it as a group!

An alternative to make it happen. Thanks.

When I was trying to use the Cubic Bezier Curve tool to create a vertical curve along the edge of a horizontal rectangular, I couldn't get the curve under control. It turned out either on the face of the rectangular or not as smooth as I expected (if I intended to keep it on blue axis). Could anyone please give me some directions please? See my screenshots as attached, also attach the correct one got from youtube tutorial.

@rodman100 said:

Try using 'Solid Tools' as you have the Pro version...
Make each unit a group. Then...Tools, Solid Tools, Trim. Pick the bottom member first then each of the 2 vertical members. see attached video.

Thanks so much for your answer and your video. It worked very well with Trim and then Outer Shell. Looks cleanly mitered by now:

I'm reading the 'Architectual Design with Sketchup' by Alexander Schreyer and came across an example of making a steel truss but I couldn't use the Outer Shell to remove all internal geometry like it said in the book that intersections can all be cleanly mitered. I don't know why I couldn't do it...

Also tried with the classic method to explode the entire truss and right click the Intersect with Model but the internal geometry is still there with the X-ray. Could someone please give me a hand here? Appreciate it...

Wow! Great answer and solution! I'll try to redo the whole thing with your great advice. Hopefully I can get it to work. Thanks.

Last time used the Solid Inspector2 to fix all surface borders, internal face edges, and short edges by creating some new geometries but this time just can't get it fixed. Should I be re-creating the whole thing with the problems? Don't get it why it gets so many short edges by using Follow Me tool to create a tube looking around a bunch of lines and curves for my logo... and how would I get those faults fixed?

Thanks guys!! Solved it! Downloaded a Solid Inspector 2 which is the best! Fixed all surfaces and everything, it's finally Solid Group in Entity Info. Thank you all.

Here's what my red base issue looks like. Thank you both that I will do some searching to try and solve it if I can't I'll come back to ask again.

I was trying to print out my sketchup model with the .stl file, but it showed red base in the 3D printing software which means there's something wrong with the designed model. Seeing a few video tutorial on YouTube, thought I had to install two plugins - Solid inspector and TT_Library which I already did. But somehow my model just can't be made solid, it keeps showing errors like:
'One or more of the selected objects is either not a solid or is locked. The non-solid/locked objects will be de-selected before this operation is performed.'
I just dont know how to make it a solid entity to be able to print out. Could anyone give me some directions please?