I didn't draw three snowmen at the same time. But I drew the first snowman from 1 p.m. until 2 p.m., then the second snowman until 3 p.m., then the third snowman until 4 p.m.
Can I use "I drew three snowmen until 4 p.m." in this case even though I drew three snowmen at the same time?
Unless there is some very convoluted context we are missing (and I can't think of any), no - it would be a weird thing to say.
It's certainly not weird to say that you did something until a certain time - for example, "I watched a movie until 4pm", would be fine. And, closer to your example, it wouldn't be weird to say "I drew until 4pm", or even "I drew snowmen until 4pm". So what's wrong with yours?
All the examples I gave indicate that before that time you were doing something, then at the given time, you stopped. Yours is different - you're making a statement of how much you achieved before a given time. When that is the point of the statement, we say that we did [x] by whatever time, rather than 'until'. For example:
I had drawn 3 snowmen by 4pm.
The same would be true with my own example above - "I had watched 3 movies by 4pm".
You could say "I drew three snowmen until 4 pm," but it's not the best choice. The reason doesn't really have to do with grammar, but with meaning.
It's just fine to use "until [time]" with an activity; you could say "I drew snowmen until 4 pm" and it would be normal. But once you report how many snowmen you drew, you're not so much describing a general activity, but reporting about progress and amount. The sentence starts to be a "measurement." This is when you would switch to "by," when we start talking about how long it takes to measure your accomplishment.
The problem is not that you're reporting multiple activities; you could report multiple general activities at once and use "until": I drew snowmen and drank hot cocoa until 4 pm.
I drew three snowmen until 4pm is a strange thing to say in any circumstance: I don't think a native English speaker would be likely to say it.
The meaning I get from it is "I was carrying out the process of drawing three snowmen, but at 4pm I had to stop and leave it unfinished", which is clearly not what you intended.
I can't think of a succinct and clear way to say what you want: perhaps I drew three snowmen by 4pm. But it depends very much on whether your point is the activity (drawing three snowmen) or the number of snowmen you drew.
I think the distinction here is that "drawing snowmen" is a continuous activity that can carry on forever, whereas "drawing three snowmen" is a discrete action that has a beginning and an end. Saying that you did a continuous activity until a particular time makes sense; saying that you did a discrete action until a particular time is meaningless - either you finished the action before 4pm in which case you weren't doing it until 4pm, or you hadn't finished it by 4pm in which case it's wrong to say you did it.
"I slept until 7am" makes sense; "I woke up until 7am" doesn't. Same distinction.
Of course there are fuzzy cases too: "I lunched until 3pm".
I really wouldn't know what you meant if you said
"I drew three snowmen until 4 p.m."
What you could say would be
it took me 3 hours to draw these 3 snowmen
This doesn't include when you drew the snowmen but how long it took another option is
It took me from 1-4 to draw these 3 snowmen
It tells you the time you spent but not exactly how long, this is I feel a bit clunky feels more like a work timesheet style answer.
or my favourite
I spent the afternoon drawing these snowmen
I would probably say,
I was drawing these three snowmen until 4 pm.
But this is probably going to depend on your situation, specifically what you're trying to express. Is the time important? Is the fact that you were occupied important? Is it something else? How you would say it and what facts you would include would vary.
In general, if you can avoid saying it, avoid saying it. Use less words.
