Ok, check my base status. I should finished my base last May let say 1 year ago but in order to advance and no be in cash trapped all the time and in need of extra parts to enhance my mechs, I balanced the base progress level by level one at the time like carousel. One mine level 5 then do next from L4 to L5 then move to the other from L4 to L5 just as example and that control gold instead to go all the ways focus in just one mine or base.
What I mean, the base need to be upgrade to get factories and mines. Just upgrade till get the 4 mines and forget about the final factory due to cost it is too high to enhance base after level 10 and farming everyday like me still not good enough to sustain the gold cost. My factories are in this example L15 just good enough to get power kits when I was able to increase level step by step later on post max out mines. The cost to make mines it is a lot cheaper than to make factory level so mines need to be first as soon you get them to get more gold out of them plus need to enhance arena shop item to be faster and more gold if need later.
Level 2 give you enough option to craft like having silver box average drops.
Level 2 will open the rare option and you can use that one to craft when it is in need after balance properly the use of gold and to have a healthy reserve at list 1.5mill and that will be ok to craft at that cost 2-3 factories and advance mechs level then back to saving and accumulate mix boxes from farming. All depend of how much you farm. No need to be that option but will help to preserve gold been low in gold reserve unless wants to hold back mechs level progress to accumulate gold for a month farming a lot and doing insane pvp to get even more gold out of it.
Sure I can use tokens and progress them just clicking but I progress them as normal player when have gold and no items to enhance. Unless the reserve of gold become very high to use L20 option forget about to enhance factories at your current level since the cost it is too high to afford. Just in the resent months I increased to L15 and you can see still have one at L11 but I keep progressing in the game.
Do not worry about to complete base factories but yes the 4 mines and when you get stronger and make more gold in pvp as example per fight then work on them one level at the time switching factories. L20 is for those playing ton of pvp and farm a lot and the cash will be there to use higher factory option and the cost it is high. Even power kit using 2 factories and farming and pvp at high rank like me, it drain your gold to be in negative balance and gold reserve will drop during that crafting unless go for 300 wins plus getting 20,000 per fight in that season.