Hi Egor,

Thank you for your response. Regarding the line guides, I currently do exactly what you suggested: I create the line and then scale it to a very high percentage. This is precisely one of the reasons why I proposed the feature of having a guide defined by two points, to avoid the line/expand/convert process.

For the circle, I will check the request. As for the length, I am aware that the guides are limited to the canvas.

Thank you again, and have a great day!

Best regards, Luca

Luca, guides in Ai are actually finite :)
You can test it by creating an 'infinite' guide, zooming all the way back, and then moving a guide down (if it’s vertical) or sideways (if it’s horizontal).
So guides in Ai are just lines with maximum allowed lengths (227 in or ~5766 mm), centered on canvas.

An ability to create an arc by three points is requested here: http://illustrator.uservoice.com/forums/333657/suggestions/34561012
The request is about having it as a live object, but it’s no real difference for your case, since we would be able to convert it into a guide anyway.

There is another method: you can specify three point with Pen by drawing an angled line and then run this script — https://github.com/Shanfan/Illustrator-Scripts-Archive/blob/master/jsx/Circumcircle.jsx — to create a circle that passes through all three points.

A canvas-long line by two points... Well, I think you can just create a simple line and then scale it something like 10000%
In most cases it’d be large enough to cover the area you need it within. An action can be recorded to combine scaling and converting into one go also.

I know these are workarounds, but these work today.

Hi Egor,

Thank you for your response. I didn't know that it was possible to rotate a guide using the Rotate Tool, and I find this feature very useful.

Regarding the 2 and 3-point guides, I am referring to guides that can be defined by two or three specific points. For example, a 2-point guide would be a straight line passing through two defined points, while a 3-point guide could be used to create a circle passing through three specific points. I know that it is possible to convert any object into a guide using View > Guides > Make Guides, but it is not possible to create a circle from three points or an infinite line from two points. Currently, it is possible to convert a line into a guide, but it is limited to its length, whereas guides should extend indefinitely.

I hope these explanations clarify my proposal. Thank you again for your help!

Best regards, Luca

Luca, Illustrator supports rotation of guides, no problem. Grab Rotate Tool and just rotate a guide. Does it work for you?

As for the '2 / 3-point guides' — can you elaborate, please? What are these and how do these work?
Illustrator allows to covert any path to a guide, with View > Guides > Make Guides, so you can have a circular guide or a freeform guide. Have you tried this?