I am trying to make a sketch of an optical setup. Currently I am using long cylinders as beampaths. (if anyone has better suggestions, those are also very welcome)

My problem is that I want to connect my beampaths, such that each one of them makes a full path (just like the light in the real setup) which seems to be astonishingly hard in blender. I would like to simply enter start and end point of the line, then create a cylinder along that, but could not yet find a way to do something like that and rather have to work with Euler angles.

The image shows the setup I have this far. Between the two lenses I want to show the four beams from the left being focused and exiting the lens setup, connecting to the right four paths.enter image description here


If I understand you correctly, you are looking for a curve with a bevel object.

When you are in objectmode, i would recommend to start with a bezier curve. go to the curve properties and there you can give it "thinckness" with a so called bevel object(has to be also a curve object).

Curve properties

I assume that you need a circle for the cilindrical shape of the ray.

you can also change the diameter by adjusting the size of the bevel object.


for getting sharp angles in your curve you also have to change the handle type of the curves vertices to vector (Shortcut: V). therefore you have to be in editmode:


If you want to connect multiple objects together, select every object you want to join and then press CTRL+J.


It is not possible to "weld" multiple curves together, because a curve vertex can only connect to two curve segments.

enter image description here

The only way is, to convert the curves to meshes (ALT + C) and then you are able to connect the parts via mesh modeling.

  • $\begingroup$ Thank you very much for the answer, this seems to be already very close to what I need. However, I am stuck at adding the Bevel Object. When I click inside of the text box, I can type Bevel Object, but nothing happens. How do I get this to work? Another question is, how do I connect multiple of these curves? Or can I just keep expending it section by section? $\endgroup$
    – mitit100
    Dec 10 '17 at 23:38
  • $\begingroup$ @mitit100 First problem: You need to create a circular curve and call it Bevel Object, then you can select Bevel Object in that textbox. (Or you could call it asdfdsjkhlkhlkjn and select asdfdsjkhlkhlkjn in the textbox. Or Circle would be a more obvious name) $\endgroup$
    – user253751
    Dec 11 '17 at 3:52
  • $\begingroup$ @mitit100 I edited my answer according to your second question. $\endgroup$
    – monatsend
    Dec 11 '17 at 13:30
  • $\begingroup$ @monatsend Thanks for the edit. How do you make the curves join together nicely? When I hit Ctrl+J, they do get grouped together in the outline, but their edges stay somewhat disconnected and they do not get patched together at all if I do not move them together already. Is there some snapping involved? immibis, thanks, this worked. Is there a way to upvote comments? $\endgroup$
    – mitit100
    Dec 11 '17 at 15:25
  • $\begingroup$ yes that's the difficulty. you have to model it by hand. but you can try to merge it with the boolean operation( youtube.com/watch?v=WxMwa0njGSM ) $\endgroup$
    – monatsend
    Dec 12 '17 at 9:46

I figured it out with your help.

The solution I found was

  1. Create Bezier curve
  2. Add the Bezier circle to give it thickness
  3. Subdivide the Bezier curve into as many sections as I need
  4. Adjust the positions of the divider as needed/calculated

The subdivision is found in Edit Mode while highlighting TWO segments that are adjacent to each other -> Curve -> Segment -> Subdivide

This will add one more segment into the curve, giving one more adjustable fixpoint in the modeling. Repeat as needed. Only downside is if you want to extend your curve, you need to move the first/last fixpoint and put the new subdivider to the place where it was before.

Picture shows the final result.


  • 1
    $\begingroup$ highlighting TWO ?vertices? You have to select the segments, which you want to subdivide. Many more adjacent vertices' segments can be subdivided during the same operation. $\endgroup$
    – Leander
    Dec 13 '17 at 19:35

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