I feel bad for asking this, but... is there any decent way to get gil that doesn't involve crafting? (outside of POTD)
A lot of it is going to be server economy specific, since the value of stuff can vary pretty heavily from server to server. Finding a buddy or two and spam maps/Aquapolis is usually decent money; the more people you bring the further the loot gets spread out, so the smallest group you can get by with is going to be the most personally profitable, and there's RNG that means any given map may end up not paying back what it cost to buy, but in general between HQ crafting mats, the Aquapolis-specific materials (Wool Top, Flannel), some of the housing items, materia, and some rare orchestrion rolls you'll end up ahead to a decent degree if you do enough.
Likewise if you can grab a couple friends and run old Coil floors, some of the drops can be worthwhile. The leg stones from T11 and the T13 chests (requires a friend to craft for max ROI, but the chest stones sell too) are still pretty valuable and frequent sellers where I am, and the music from T12 goes for a decent chunk. Turn in the actual loot drops for GC seals, spend the GC seals buying mats to sell on the MB.
Also if you have LTW at like level 30 you can unlock leatherworker Desynth, run to Ul'dah, and blow up shoes for Fieldcraft Demimateria 3s. If your server's going rate is over 40k you should make money overall (~300k in shoes should average 10 FC3s, so selling at 40k is a modest profit after market tax, going up as you sell for higher.)
If you can send your squadron guys out for blue scrips, you can make OK money for no investment flipping the scrip crafting mats, too.
A lot of it depends on how much gil you're trying to make when you talk about making gil; if you're looking to gil cap you're going to have to do a lot of playing the market board and controlling crafting markets to get there. The above if you're semi-diligent about it should be enough to build a comfortable gil buffer before SB hits (well over medium house price, not enough for large, most likely), though.