Currently, "Enhancement Cores" are achievable by Banshee's and Clan Bounties, Legend Nightfall or Legend/Master Lost Sectors.
The Problem is, these sources are not giving enough to fullfill day to day weapon masterwork requirements. At least for me as a new player.
I think it would be better if the quantity of Enhancement Cores from all these activites are just get doubled. Or just give some option to trade Enhancement Prism for Cores. I always have more Prism than Cores even sometimes Cores get below Ascendant Shards. Please Bungie, just take 1 Ascendant Shard and give me 50 cores if possible.
I think everyone would've faced this problem once and doubling the Core drops will make things easier.
They can also drop when anytime you get a legendary piece of gear or dismantle a legendary weapon.
If you are still sitting on a pile of Vanguard tokens, I highly suggest cashing those in before Tuesday.
[b]How many weapons are you masterworking?[/b]
The point of the economy isn't that you get to masterwork everything. Its supposed to be a capstone for when you find that ONE version of a weapon that you think is "perfect"...and you want to maximize its power/potential.
I play everyday, and if I masterwork two or three weapons a season....that's a strong season. The only armor pieces that I masterwork with any regularity are exotics I use very fequently that have the stat distributiosn that I want....and class items (because I want all 10 energy levels...and they are reusable).
Edit: Looking at your characters, it looks like you're trying to masterwork everything...and that's not what the game's economy was designed for. So naturally you're getting caught in a bottleneck that was designed specifically to make what you're trying to do VERY difficult.
All you have to do is collect the bounties and play a variety of activities with the required weapons. The bounties practically auto complete themselves.
Currently, I have 3,000+ cores. At the end of next season the quantity will be 4,000+.