Help with joins / soldering

[Jojow82]

Hi there - I'm trying to perfect this ring design, currently using one length of silver and joining the 'shape' part on the inner side. Is it a case if filing the end at a precise angle to get the seamless joint? wondering if I should be looking at doing the shape seperate insead as I can't quite get it exact without slightly thinning the join when filing to get absolutely smooth? It's very slight but you can see on the left hand side / join - it's very slightly thinner. Can anyone recommend a clamp to help keep the join tight when soldering too? Apologies if this all sounds a little ameteur! Thought someone here might have suggestions...