# Want to make a cavity in one shape the same dimensions as another shape
**URL:** https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704
**Category:** Modeling Questions
**Created:** [January 5, 2021, 4:23am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704 "2021-01-05T04:23:36Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@Spark](https://discourse.shapr3d.com/u/Spark)
#### Post date: [January 5, 2021, 4:23am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/1 "2021-01-05T04:23:36Z")
Super new to cad design, so please forgive me if this is just unreasonable or even not possible.
I’m trying to design a tree in 2 parts. A base and a top. Plan on making multiple top designs so the base can fit all tops. How do I make a hole in the bottom of the treetop that is the same shape and dimensions of the top of the base? I hope that makes sense. I tried uploading both files to mesh mixer and flip normal the base to make an imprint in the treetop, but it didna work. Any way to do this in Shapr3D? Any ideas or tips would be hugely appreciated.
Cheers
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### Author:  [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)
#### Post date: [January 5, 2021, 5:15am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/2 "2021-01-05T05:15:56Z")
A rough drawing can help us visualize your need.
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### Author:  [@Spark](https://discourse.shapr3d.com/u/Spark)
#### Post date: [January 5, 2021, 5:32am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/3 "2021-01-05T05:32:08Z")
These two objects. The plan was to have the top slide onto the base.
Does that help?
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### Author:  [@NathanD](https://discourse.shapr3d.com/u/NathanD)
#### Post date: [January 5, 2021, 7:19am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/4 "2021-01-05T07:19:11Z")
Try this @Spark,
Place the top on the base where you will want it positioned while installed.
Using SUBTRACT tool, select the base and the top, being sure to select what part you want to subtract (the base) and the part you want to subtract from (the top)
On the side bar, under the SUBTRACT settings symbol, select “Keep originals” of REMOVED BODIES.
You should be left with your original bodies, but the top body will have a hole in it that matches the base.
Hope this helps.
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### Author:  [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)
#### Post date: [January 5, 2021, 5:23pm UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/5 "2021-01-05T17:23:06Z")
NathanD has the fix. Look up Boolean: Add, Subtract, Intersect. Extensively used on modeling.
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### Author:  [@Spark](https://discourse.shapr3d.com/u/Spark)
#### Post date: [January 6, 2021, 3:22am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/6 "2021-01-06T03:22:43Z")
Thanks @Oregonerd and @NathanD! I’ll give it a go and report back.
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### Author:  [@Spark](https://discourse.shapr3d.com/u/Spark)
#### Post date: [January 8, 2021, 1:16am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/7 "2021-01-08T01:16:55Z")
Worked like a charm gents! Thank you.
Cheers
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### Author:  [@Oregonerd](https://discourse.shapr3d.com/u/Oregonerd)
#### Post date: [January 8, 2021, 5:29am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/8 "2021-01-08T05:29:06Z")
It’s good idea to make a copy of the object before you subtract from it. You will be happy you did if you want to make a change to it later.
Shapr sometimes won’t let you go back. Sometimes so you have to remake the object. A copy comes in handy for those times.
You can keep such copies in a COPY folder and hide it.
Shapr is direct modeling, and is not history based.
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### Author:  [@Spark](https://discourse.shapr3d.com/u/Spark)
#### Post date: [January 12, 2021, 5:20am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/9 "2021-01-12T05:20:07Z")
This is a great idea! Thanks for the heads up!
BTW, is there like a new users thread to ask newb questions so as not to clog up the forum with lots of threads asking simple questions? If not, would it be ok for me to make one?
I have a new task that’s driving me nutty. Customer wants me to build potted planters, but wants them to have a ridged texture like as if it was sculpted. Want to ask, but know in other forums I’m in, it’s generally frowned upon to post a ton of new topics. I’ll admit, I haven’t spent much time searching so far lolz.
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### Author:  [@KPeter](https://discourse.shapr3d.com/u/KPeter)
#### Post date: [January 12, 2021, 10:00am UTC](https://discourse.shapr3d.com/t/want-to-make-a-cavity-in-one-shape-the-same-dimensions-as-another-shape/10704/10 "2021-01-12T10:00:50Z")
Feel free to create a topic for the project, there you can flood all your questions 🙂