Making a snake out of four discrete cables is certainly an option, and if you have the materials already at hand, it's a frugal approach as well. But it's going to be needlessly bulky.
Studios and live production companies use big multichannel snakes all the time. If you compare a relatively simple 12-channel XLR snake with the combined size of 12 individual XLR cables, there is a huge difference in size. Why? Each XLR cable will have conductors that are wrapped in a shield, inside a rubber jacket. There is a lot of redundant packaging, compounded by every additional line. Audio XLR snakes have lots of individual conductors, often in a group that is shielded, which are then all wrapped inside a final ground shield, and ultimately wrapped in a single outer sheath to protect them. There are plenty of sources for multichannel low / high impedance bulk cable, and you can then solder you own ends onto the cable.
My $0.02: when fabricating a custom cable assembly, prioritize reliability, ease of use, weight, and size. Professional multipin connectors make setup much faster and eliminate patching errors, so you might consider using a Neutrik 8 pin XLR at each end, instead of 4 x 1/4 inch phone plugs (provided you can integrate the corresponding jack on your gear or mount a connection D box at each end).
