Hey, one of the first modules I ever wanted was a Livewire Vulcan Modulator http://www.analoguehaven.com/livewire/vulcanmodulator/
Simply put, this is a dual LFO where each oscillator has FM on its output. (There are additional outputs for sum/difference/min/max.) It’s not hard to patch two LFO’s together, although many LFO’s out there don’t have FM CV attenuators.
I’m just wondering if there is anything like this pre-built out there?
also: first post! hi!
take two or more Bogaudio LLFOs and cross modulate them
take 2 or more nysthi lfomultiphase and cross modulate 
LLFO doesn’t have FM attenuation. you can use the scale controls for a similar effect, but that would mean altering the downstream modulation, which is not ideal. What I’m trying to avoid is external attenuverters.
the wave morphing does resemble the Vulcan’s “symmetry” control. I’ll look into it.
A dedicated dual module might, in principle, have CV ins for A->B and B->A mod amount, essentially an internal VCA on the strength of the FM.
I mean, it’s a modular world. I can build these things myself using modules, but, like I said, the Vulcan was like the very first thing that got me dreaming of modular.
Whats the problem?
A tiny case or not enough cables? 
Somebody recently liked this post, so I’ll just bump this to say merely that the best module I’ve found for this purpose is a pair of Fundamental LFO-1 modules. They take up a lot of HP, but they’re polyphonic, so slap a PolyCon and split on there and you got a great Caudal alternative for random-ish smooth modulation. (For added spice, use a third LFO for amplitude modulation.)
RJModules Twin LFO … but it works at 0-5V
two channels of mutable stages in looping mode
Twin LFO has one osc modulating another; the sound I want requires each osc to modulate the other.
Two channels of stages would work if you add an 8vert or other attenuator. Likewise the Mental Quad LFO. the MLFO from MSM seems like it ought to work, but the phases of the two oscillators are locked together somehow… (I wasn’t able to get the FM on OSCiX to work at all, seems to be a bug…)
Do you want FM modulation? The submarine PO-204 has 4 frequency linked oscillators with phase modulation inputs.
I love the PO-204! Phase modulation is my jam. Patching it can get a little messy with all the VCA’s and envelopes you need for typical FM architecture, but that’s modular synths for you.