Answers.Body: <p>Well, that tile wouldn't go <em>underneath</em> a plate. But <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=2654" rel="noreferrer">a 2x2 round plate with rounded bottom</a> has often been used in official sets to allow vehicles (such as boats) to easily slide over carpet, and might be just what you're looking for.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-02-03T08:35:40.693Z
Answers.Text: I'm not sure this is what OP asks for, as the question talks about a brick, while the linked piece is a plate, and the question mentions using it "to keep the roof from moving", not to easily slide. Seeing these contradictions and the acceptance of your answer makes for a confusing situation, but hopefully OP can clear their intentions up.
Answers.UserDisplayName: zovits
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-02-03T17:51:09.937Z
Answers.Text: Well, any brick would connect under a plate, so I assumed that wasn't what the question was about. And (if memory serves) even Lego themselves use the word *brick* to mean *any Lego piece*, so I think it's a reasonable answer. It is often used to keep pieces from shifting relative to each other, so would work well with a bunch of plates used as a large roof, but still look nice doing it.
Answers.UserDisplayName: RSchulz
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-02-02T23:22:38.713Z
Answers.LastActivityDate: 2021-02-02T23:22:38.713Z
Answers.UserDisplayName: RSchulz
Body: <p>I am trying to create a modular building with roofs.</p>
  <p>I saw this Youtube video and I would like to know what is the round 2x2 piece mentioned by the author.</p>
  <p><a href="https://youtu.be/3oq3XPN8brQ?t=165" rel="nofollow noreferrer">https://youtu.be/3oq3XPN8brQ?t=165</a></p>
  <p>What is this piece's name?</p>
  <p>Thanks, Benoît</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-03T08:32:17.023Z
Comments.Text: Hi Benoit! You are certainly free to post links to Youtube videos, in fact it would help identify the actual use case here (what is the problem to be solved and what the video author suggests).
Comments.UserDisplayName: zovits
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2021-02-04T15:32:42.607Z
Comments.Text: Thanks for positioning the video at the right place! So it turns out my guess was the piece you were looking for, so it all worked out.
Comments.UserDisplayName: RSchulz
Tags: <piece-information>
Title: Round 2x2 piece that goes underneath plate
UserDisplayName: Benoit Goderre
ThreadText: # Round 2x2 piece that goes underneath plate
  
  (Asked by: username_0 on 2021-02-02)
  
  I am trying to create a modular building with roofs.
  
  I saw this Youtube video and I would like to know what is the round 2x2 piece mentioned by the author.
  
  <https://youtu.be/3oq3XPN8brQ?t=165>
  
  What is this piece's name?
  
  Thanks, Benoît
  
  **Tags:** piece-information
  
  > **Comments:**
  > **username_1**: Hi username_0! You are certainly free to post links to Youtube videos, in fact it would help identify the actual use case here (what is the problem to be solved and what the video author suggests).  
  > **username_2**: Thanks for positioning the video at the right place! So it turns out my guess was the piece you were looking for, so it all worked out.  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_2 on 2021-02-02. Score: 6 | Accepted answer
  
  Well, that tile wouldn't go *underneath* a plate. But [a 2x2 round plate with rounded bottom](https://www.bricklink.com/v2/catalog/catalogitem.page?P=2654) has often been used in official sets to allow vehicles (such as boats) to easily slide over carpet, and might be just what you're looking for.
  
  > **Comments:**
  > **username_1**: I'm not sure this is what OP asks for, as the question talks about a brick, while the linked piece is a plate, and the question mentions using it "to keep the roof from moving", not to easily slide. Seeing these contradictions and the acceptance of your answer makes for a confusing situation, but hopefully OP can clear their intentions up.  
  > **username_2**: Well, any brick would connect under a plate, so I assumed that wasn't what the question was about. And (if memory serves) even Lego themselves use the word *brick* to mean *any Lego piece*, so I think it's a reasonable answer. It is often used to keep pieces from shifting relative to each other, so would work well with a bunch of plates used as a large roof, but still look nice doing it.  
  
  ---
  
  