When I extrude the profile along a closed path the profile has uneven thickness at certain points (see the first screenshot).
Is it possible to use a closed curved path with Bevel applied an have even thickness all around?
Closed Curves Path with Bevel applied:
The profile has uneven thickness
Open Curves Path with Bevel applied:
The profile has even thickness
Hey Bram,
Just a quick idea I had would be to use the 3D cursor as your pivot point. Put it in the middle (from both front and side views), and then it should all extrude toward that point.
I haven’t done that part of the challenge, so if what I said doesn’t work, I will take the time to do it.
Hope that helps~
Jey @James_Ran, unfortunately your solution didn’t work or maybe I am doing it wrong. I guess it has something to do with the sharp bend the curve has to make at the bottom and that deforms the profile the closed curve path is using. Maybe the sharp bend makes the width of the profile changing. I still find this sort of behavior kind a odd do 
Hmm, that’s a shame then.
The only other thing off the top of my head I can think of is either to bring the bottom part of the curve closer together and/or angling the curve handles differently. You might need to rotate them from the front view either vertical, horizontal, or at 45 degree angle.
Or you can grab the inner edge of the window to the corners using the Median Point and scale it smaller on the X-axis. And then grab the outer (bottom) edge to the corners and scale them larger on the X-axis.
That should solve the issue even though that might not be the best solution.
I think the actual issue would be the curve handles, but I’ll need to try it when I wake up later. 
Hi @James_Ran I attached my window .blend file to this message, so you can check and test on the file yourself.
I have two curves:
Frame_Path
and
Frame_Profile
I use the Frame_Profile to Bevel the Frame_Path… but because the Frame_Path makes a 45 degree at the two bottom corners it narrows the bevel.
Window_LOD_B_4x0-5x4_02.SOURCE.blend (537.7 KB)
Hey Mr @Bram_van_Vliet
I have another solution temporarily til I figure out a better one.
If you go into Edit Mode with your Frame_Path_Closed, select the bottom two corner vertices, press Shortcut W for Specials menu, and choose Set Curve Radius to like 1.430, then it will fix the issue visually for the angle from the front.
The problem is it makes the width of the frame much wider at the bottom vs the top. So you might like it or you might not. But I’ll edit my post or make a new reply when I figure something else out hopefully soon.
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Ok, so if you do what I said previously, two more steps and it will be what you want. The downside is you have to convert it to a mesh, but you can keep a copy of the original Frame_Path_Closed with the toggle option in Operations Menu or simply duplicating it.
So after you set the Curve Radius to your desire, convert the Frame_Path_Closed to a mesh with Shortcut ALT+C while in Object Mode.
Then select the 45 degree Edge Loops of both corners at the bottom, turn on Individual Origins pivot point, and then Scale them both on the Y-axis to your desire. This will retain the fixed pinching from what I previously said and allow you to fix the new width problem.
I HOPE that will be what you need. Remember, you can leave the curve as a curve til the end, or you can simply make a backup curve of it.
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Victory is ours!~
Good morning/evening @James_Ran
Your solution worked perfectly, thank you for your clear and thorough answer. This looks much nicer and way better than before.
Victory is ours 
OK, this was a while ago but…
This is how I would fix that.
The problem is the rotation around Origin.
It’s the part between the green arrow and the origin that gets warped on a sharp bend, so…
Put the origin (or the mesh) so that there will be no overlap in the sharp turn…
… this means that I have to scale down the path a little at first …
… the scale it up to get the good applikation…
