Operating an offset function to a line, the both sides option is not kept between operations.
That is, you have to reselect each individual line, then select the both sides option again and again. Also it is impossible to select a group of lines and apply the double sides offset to all of the at once.
.F
Yes, it is this way also in the Windows version of Rhino. Don’t know why this option is not “sticky”.
Yes, same as above. Offset does not take multiple curve inputs - I’m assuming because the results would be unpredictable if all the curves are not planar. So for this you currently need a script. Unfortunately, my current multiple offset scripts are all programmed in VB, so they do not run on Mac; and I haven’t time to convert them to Python for the moment.
–Mitch
Nothing too unpredictable if you offset a group of lines both sided, i guess.
Yes, if they’re all only lines. But you can offset any kind of curve in Rhino, so the command has been tailored for the general case.
– Mitch
I had some time to “translate” my offset multi-curve 2 sides script into Python. Attached below. I have NOT tested it on Mac yet though…
Offsets open and closed planar curves both sides, with choice of end style for the open curves. Both open and closed curves can be run together. Non-planar curves will be refused; lines will use active view CPlane, so make sure the view you want is active. Should remember the last-used settings.
Can’t guarantee that the ends will always work. Also Offset is in itself not extremely unreliable, so some types of curves might fail or offset incorrectly. Use at your own risk… 
–Mitch
OffsetMulticrvs2SidesWEnds.py (5.7 KB)
Hey I know this is really old, but this problem still isn’t solved as far as I know. I’m making a floor plan, and right now I just offset my (rectangle) rooms 50mm on both sides to get my preferred wall thickness of a 100mm. But I have to type ‘b’ every single time to get the both sides of my rooms. Like you say, it doesn’t stick like a lot of other functions do.
Have you found a solution in the last 10 years? 
if you have an alias for your offset simply use this macro below, or create a new alias and copy it into it. OB for instance works fine, with the hidden command Testinstantalias you can make it instantly, then hitting OB without hitting space or enter will make all the magic for you. it works with preselecting the curve either.
Offset b pause
Hey thanks for replying! I’m somewhat of a beginner to Rhino, so could you explain it in a couple more steps? I don’t know macro’s and aliases that well.
are you using a mac version?
in your Rhino Settings find the tab Aliases, there you create a new one (OB for instance) and copy past the macro into it. it will then show up in your commands. with the test command you make it work faster thats all
I’m on Windows 11. So with his, if I type OB into, it will always be BothSides? And then when I type Offset it won’t?
I see now you’re replying to my reply to the main topic. That’s why it might be confusing that I have no Mac. I also have a thread of my own on this topic!
yes with this alias the setting b will make it both, this works on all other commands when you look carefully there will be one letter underlined indicating that this letter can be used as a switch.
the regular offset will stay unaffected
the same is valid for windows so no worries.
That’s awesome! I’m going to try this! I also wanted to make 3 Point Rectangle stick instead of the normal. Then I would have to do Rectangle p pause?
i believe so, but best you try it before somebody dies on it 
It works! Thank you so much! This will save me lots of time! And thanks for introducing me to Aliases in general! I’ll be able to make some good ones. I guess deleting an alias in the future will just bring everything back to normal?
it will just delete the preformatted alias you have created, it will not change anything, if you dont need it for a while just leave it there you might need it again one day.
just to be sure there is no misunderstanding, it does not change your regular command, a macro is basically just a stored pretyped command simulating you typing the options thats all. you can save several aliases for the same command with different options if you need it. so no worries.
Yes, but that’s EXACTLY what I wanted, even better than what I asked for! This is just a little bit quicker than typing offset and then ‘b’, but since I need it so often it’ll save loads of time!