Hi all may be off topic for this forum I just thought I would give it a shot.
I designed a simple pencil holder, but there is a line indentation around the bottom I don’t know how to create any ideas about how this is done. I know it’s simple I just don’t know how.
Uhmmmm… aren’t you forgetting something? Like… ohhh… I don’t know… WHAT CAD ARE YOU USING!!! 
At any rate, you can do this in the slice even though it’s much more work than with CAD.
One way that first comes to mind is to use the negative modifier in the slicer. My examples are going to use Orca Slicer, it’s just a better all around better version of Bambu Studio and has many more features and none of the forced Bambu Makerworld advertising. But this example should also work in Studio. I’ll be using the Torus primitive and since I don’t have your model, I simply use a cylinder primitive to mimic the cup.
Right Click and select Add negative part and use Torus
Using the Top Down view, scale the Torus so that the inner diameter is just smaller than the diameter of the cup. You will have to eyeball this but I’ll show a possible shortcut using the caliper tool which is only available in Orca.
Select the Torus(easier to do in the object menu) and use the (M)ove command to orient it correctly. You might find it easier to select each object individually and simply right-click and select center. Do this individually not the entire assembly and it will move the model and the modifier to the center of the plate.
Then slice
One of the many CAD-Like features baked into Orca that Bambu Studio has not yet incorporated is the Caliper tool. Here is how that works in this scenario.
Yea, what are you actually asking?
Title says “CAD help”, but you state you have “created” the part shown- that already has the line…
My apologies, the file shown is a downloaded stl file. I am in the process of recreating files that I want to teach myself and not just searching for templates as a crutch.
I am using fusion 360. I did create the pencil holder I just was not able to add the indented line around it.
My apologies @Olias I am using Fusion 360, but this is also very helpful, thank you so kindly for your time.
Ah,
Look up the revolve function. You can either use a single sketch of the entire profile of the pencil holder, including the slot, and revolve everything into a 3D model, or add a sketch of the profile of the slot you want on the right origin plane, and revolve/cut the sketch away from the existing model.
Thanks @binfordw I was up until 3am working through tutorials, and when I woke something like that came to mind. You are absolutely right that will work in fusion. Thanks again for your response.
I also would use the Fusion Revolve function, since it is a fairly simple profile, but another way would be with Modify>Combine.
Make the cylinder, and also make a ring with the correct inner diameter and thickness, Move the ring into position, then Combine the cylinder(target) with the ring (tool) as a Cut. This is a more powerful tool that allows for cutting with complex shapes. Like this curved triangular recess inside a cylinder for a catch:
I will not admit how long I spent trying to create this tiny feature before I realized “Combine” could also mean “remove”, but the time could be measured in days.
I just did a quickie version in Fusion by creating this side sketch with that notch built in and adding dimensions. Then I revolved that sketch into the solid. I could then edit the sketch and modify the dimensions until I got the shape I wanted. Hope this helps.
Thanks, @sprior and @lkraus so very much for your time and insight. I spent hours pounding my head on how to make a simple indention.
I’m 10 years in to the Fusion 360 learning curve for hobby use, it still has me banging my head on the desk every once in a while.
