Are there any way to farm legendary shields beyond the Grinder?

I've understood that you can try to farm legendaries weapons at the Grinder using correct recipes. However I haven't found any ways to farm legendary shields. I'm trying to get The Sham. So far the only other ways I'm aware of getting a legendary shield are:

• Spamming Nina's machines hoping for luck.
• Getting lucky on story bosses (unfortunately, unless I'm mistaken you can't farm those once they're dead).

Are there any reliable ways to farm legendary shields in Borderlands: The Pre-Sequel?

Solution 1:

In the last DLC Claptastic Voyage, there is a "simple" way to farm legendary shields.

You simply beat the DLC Boss over and over again. You'll get a random legendary shield with a 50% chance (at least in my experience). Ofc, he is extremely strong, so I'd recommend a few friends with enough firepower. In the past week, I've beaten him about 11 times and found a reogenator, a prismatic bulwark, a sham, a shooting star, a WTF and a kala (Only tested in UVHM).

The Sham itself can be farmed more easy by killing the RK-5 Jet, who has an increased droprate.