Ok First: Though an
iris kit would totally do the trick they un-fortunately cost about $120.
Also, what's wrong with "square" light? If you
roll the
barrel you give the edges a very frosted look without lossing
intensity of the light like diffusion will do. People won't really notice the squared light if you do that. So I don't see what would be the big deal with squared light with soft edges (you usually soften the edges of all lights anyway).
However, assuming you HAVE to have rounded light for a reason I can't seem to see right now (other than specials but I doubt you're using that many specials) the only ways I can see you being able to give a rouned but small light are ethier:
a) the previously mentioned "
gobo" idea, making your own or buying one
b)
iris - thought quite expensive so I doubt it's even an option in your case
c) Buying new barrels for your lights (probably 50 degrees) however this will also prove costly and probably once again not the solution you seek.
d) Or possibly (never tried this) using black rap at the front of the light like a
barn door but carefully shuttering the wrap to give a "rounded"
effect. I don't know how well this would work, and it would look terrible and have a potential to fall off, but it's just a thought. An extrmelely far fetched thought that I probably wouldn't use, I'd probably deal with the "square" light with soften edges, assuming I had nothing else to work with and no budget.
You asked about a
snoot working, and no, I don't believe it would. The purpose of snoots (aka top-hats) are to stop the
spill of light from the
fixture, usually used on lights that hang over the audience. I don't think they change the size of the beam and if they do, they don't change it by much, atleast not enough for what you're probably looking for if at all.
There may be other ways, unfortunately none have come to me in the time it took to write this.