R.B. Crystron

Essentially, you're adding Machine of the Closed Heaven (Booster) so you can make Machinesmith's Desirae (Booster pointing at an arm w/ Funk Dock) as either an additional endboard piece, or as a backup plan if you get handtrapped too much. Best case, you can end on Infinity + Tristaros + Cluster + Dragster + Booster/Dock/Arm, but that's a ~3 card combo. It's also not awful to open RB, fire a Rocket as a boardbreaker/interaction bait, and then still get full Crystron after (eg: Special Limb > Normal Smiger > Link Booster add Dock > Dock add Rocket > Rocket inherent summon > Rocket effect > Dock summon > Banish Smiger to add Inclusion > Play normally).

The basic endboard combo to add RB requires summoning Prasiortle somehow, and having any Crystron monster in hand (added by Eleskeletus, Thystvern):

Summon Prasiortle > link Clockwork Knight > Prasiortle summon from hand > Link 2 Booster w/ Clockwork + Crystron > add Dock > Dock, add Driller/Cutter > Booster effect, summon from hand.

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Unfortunately, they haven't printed Machinesmith's Requiem yet, so none of the RB parts are starters on their own, but Driller and Rocket are viable for 2-card combos into full Crystron, whereas Cutter can only 2-card into Booster/Brute unless you run Hi-Speedroid Kendama or something (Powered Inzektron doesn't work, Tristaros can't pop it).

I'm not that happy with only having 15 non-engine, but 2x Driller, 2x Rocket, 3x Tristaros is kinda needed to plug the consistency gaps. And yeah, 3x Tristaros, people usually run it at 2 because it's dead on its own, but it's a good card when paired with a special summon starter - 5/6 main deck RBs are synchro pairings.

R.B. Stage Landing is 0-1 in this deck because the lock makes it a brick in most hands, but it's still worth considering as a 1-of because on its own it's a 1-card RB combo, and also turns Dock into a 1-card combo. Last 2 extra deck slots are flex.