Both the ADDAC506 and the TEIA randomize the Attack and Decay portion of the Envelope with each hit. The ADDAC is a quad version of the TEIA, with some extra options. To the best of my knowledge the TEIA is no longer available, but the ADDAC one most certainly is. As stated, I own both as I really enjoyed the TEIA so I liked being able to have more of the same. You can set the minimum and maximum level for both the Attack and the Decay parameters, which means you define the range within which the randomization takes place for either. Each hit of your bow won’t have the exact same characteristics.
I hope this makes sense.
Let us know how that goes. I’m having a hard time believing the “woodiness” of my patches. Are you referring to a specific example of yours? Any recordings I could listen to? I’m probably doing it wrong. 
I’ve been reading around, and run across this beautiful thread on MW. I wasn’t aware of the Haible String Filter but I have to admit both the examples and the description have me hooked!
There doesn’t seem to be an official, or even a DIY, Eurorack version. I reached out to Random*Source to ask if that will be a possibility in the future. I intend to buy a couple of PCBs and give this a shot. It sounds really nice!
Thanks! It shouldn’t be far away now. I’ll see if I can post some IG videos when I receive a finalized unit. The module is based on the basic components we’ve discussed earlier, which makes is both useful as a RoC module while leaving it open to other patch uses.
Unfortunately I’m still ways away from recording. Here’s the original recording from regenbot that inspired me to pick one up. I was amazed by the timbre of the lower pitched melody (this is double track recording of Mysteron on both voices). He’s using a ribbon controller patched to the Pitch and Morph (or whatever it’s called) input.