You can use a standard coaxial RG-6 quad shield cable for audio and you will have solid results. Better is braided cabling, like that which you see the Blue Jeans Cable uses with Canare connectors.
I typically just get the premium cabling from Monoprice and have great results with their stuff.
If I go custom, more often than not I use Extron Mini-High Resolution RG59 cabling (MHR cable) and use F-Conn connectors which are a compression RCA connector, and likewise have solid results.
There are a ton of cables you can make yourself and will provide solid results, but if it is a one-off operation which you won't be repeating, then I would likely just order the cables from someone and be done with it as the tools and piecemeal ordering will likely be more expensive than ordering just what you need.