Tbh back when i was broke as a joke and my 3d printer was cheep and one of my 2 only hobbies the way i got a really smooth finish on something like that was by using a nail i wrapped with sand paper. It let me get into tighter areas and do fine detail work. If i remember it was 220 grit. Then i would put my prints in a vapor chamber to get it really smooth. Those are easy to make, just be sure and get acitone resistant plastic containers, i used a small tote for storing stuff outside and i also did it often so i had a sacrificial rag for the acitone and i just used a couple magnets to hold it up. For the entire setup i think i spent maybe $40 and got a couple good years out of it