How would I create an Arch shaped tunnel with Roblox Studio

I am trying to create a realistic city and am trying to create road tunnels. I cannot make a smooth looking arch that continues through the arch.
What I have tried:
I have tried the following: I have tried to use parts to create a union and then negate it but that did not seem to work.
Next, I tried using a building tools plugin to overlap parts. I could make a thin arch but it was not that smooth nor long enough.
My Request:
I would appreciate it if someone could tell me a reliable method to make a long smooth arch with: Roblox Studio base tools or any plugins.(I would appreciate A link to any plugins that are mentioned)


You could make a large cylinder and cut out the arch from that.

In what way and with what tools could I do that with?

Use the negate option in the model tab and then union

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I have already tried that but will try again. Thank you!!!

I have tried that but when I press negate I juts have a translucent red cylinder and no hole.

Negate Could be Useful

Use Unions. Make the arch and then put some parts in the area you want the players to walk through. Negate them and union the arch. That is all you have to do. Also Union the negate with the Arch so it will work.

Union the negate with the arch?

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Yes, It cuts a hole in the Union to where players would be able to walk through.

Do i have to union just the cylinder or the wall which the arch will be in? Or both?

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The Negate will only cut the parts it is unioned with

So I unioned the cylinder and but it near the wall. When I clicked negate I got know hole an just a red transparent cylinder. Does the cylinder have to be inside of it? What am I doing wrong?

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Everything must be one union, Send A screenshot and i can show you. Also when you save make sure to group it because Roblox has a problem.

They are both unioned.

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Here is what you are doing wrong:
Only Negate the one part that you want cut. Don’t negate the whole wall. What you dont want cut should stay as a part.

Not Unioned:


HIGHLY reccomend this plugin for arches! its super useful AND you can avoid pesky unions that cause latency in game!

Unions can cause incorrect collisions and are just messy as a bunch, I suggest you stay away from them.

(Just an example of what the plugin does)
the “30” is the angle you want, the smaller the angle, the wider your arch will be
“Render Circle” creates a full 360 circle using the angle chosen and the part

It’s really fun to use and I use it quite often!


I negated my cylinder and then unioned both parts my cylinder dissapearded without leaving a hole.

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That sometimes happens, When you save make sure to click on the union first then do Ctrl + G. It will stop that from happening. Also, just redo it if that happens.

Thank you! With some fiddling and changing the detentions it worked.

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Make sure to mark him as solution so people who stumbles across this thread will know what to do

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