The way with lemon juice is wrong - it's not smetana, it's mayonaise.

You could do a smetana with separator, but, as I understood, you don't have one.
You could try find fat not-pasterised milk (you won't find it in supermarkets, only on farm - fortunately, in Russia it's not a problem) and leave it in a bottle in your refrigerator for a night or a day. You'll see thin layer of a little bit dense white liquid - it's smetana. Collect it with a spoon and put in some crock. It can taste a little bit sour. You can whip it - then it'll become denser.
My granny do a smetana that way, because she lives in the city and has no possibility to use separator.