I have three of those sentry and I believe that is the stock color yellow

Nice work,ryanG88 ! I'm assuming you purchased your Cage casts from clayorrnotcustoms ? Just ordered a set myself as I refuse to give friggin eBay scalpers 100 plus bucks for a SDCC LC!!!! And if I may make a suggestion ? If you are not into sculpting like me, you can use the wrist gauntlets (modified) from the Thanos wave BAF for the top of his boot cuffs. I already tried it and it looks pretty good. Lastly (and I ask this question a lot of Realmers), what yellow paint did you use here ? Was it something that matched the original or did you have to repaint the whole thing ? Thanks, and welcome (belatedly) to The Realm.

Hey!
That's for the comment. 100% going to try that method with the Thanos baf gauntlets.
As for your question. I used citadel yellow paint. Blended very well with the OG color. Did a light wash over the body just to blend in the top painted part a bit better.