Ohhh now this is gonna be a fun thread! I love to make synthy sounds with a various combo of pedals.
In regards to the Red Ripper it CAN get synth like on its own but REALLY shines with an filter or pitch-shifter after it.
Heres one of my many favs:
Boss OC-2 (-1 full, dir at 09:00) > Tech 21 Red Ripper (vol unity, treb and low at 2:00,mids at 3:00, drive at 2:30 and RIP at noon) > Dunlop Bass Wah (lets use % I use it in the 60-80% range): this makes for a responsive and FAT synth tone. I mean responsive because the Red Ripper reacts to how much you dig in. With a soft touch you get a low growl and when you dig in it literally sounds like a R-I-P growl.
WMD Geiger Counter (waveform C3, tone disabled, gain at 12:00, vol unity, sample reduce at 3:00, bits full) > EHX H.O.G. (use -1,+1 and +1/5th, freq and res at 5/10, freeze-gliss set to gliss but not freeze) > Roland RE-20 Space Echo (mode 4, bass/treb at 1:00, echo full, intensity at 1:30, rate 9:00) This one can't really be explained.. (I'll have to post a soundclip of it soon)
I have a ton more and if need be I'll post more (possibly with some videos/sound clips to stop my poor attempts of explaining a sound)