It is totally doable to put together your own curriculum with the CM method, though it does take some work. There have been years when our budget was very tight and a math curriculum and used books was all we purchased. Are you just talking for history or for all subjects? For history I did it like this:
Decide how many days you will read a family spine for the year, and how many pages are reasonable for your family. For us: 5 pages a day x about 150 days = 750 pages. Thats a lot for us, we tend to have a lot of “life skills” days, so I would usually call it 500 and look for a spine about 500 pages long. I would search around for something for our selected time period, 500 pages, in public domain. If I cant find anything I would start with my favorite lists and see what I could find used. That would go on the family schedule 4 days a week. I would search the internet for maps of the geographical area to use once per week. We would also add dates to a book of centuries weekly (SCM offers a free one you can print out). I ask for oral narrations daily and one written narration a week in history.
Next I would determine how many pages of history each child can handle, and do the same basic math as above. So if I decide they can read 1000 pages of history in a year I search for books related to the time period, usually a combo of biography and historical fiction. Trying to keep the total pages to about 1000. I try to use the library for these. Or public domain, or used.
You can use the above method with the books recommended by SCM or your own. The great thing about he guide is the pacing of course, but also the teacher notes help with discussion, and the narration notecards are super helpful.
You can easily do artist, composer and poetry using the internet and the library, which I have done. I will admit we enjoy the study more when we are able to get SCM plans for those subjects. They include easy to follow schedules and interesting notes for people like me that don’t really know anything about those subjects.
I dont know if that is helpful, but it can definitely be done without a guide.