I bought a 3D printer and felt that the accuracy was not very good. How to solve it?

I bought a desktop printer to print parts of an open source project. I think the original words in the project are: ABS is better than PLA, and PLA is also OK. Then I consulted the merchant and he said that the strength of the light-cured parts is not enough. As a result, the parts printed by my FDM could not be closed. I regret it a little bit, I feel that it is not as good as light-curing, and the price is not much different.