What are you making these sounds with because for the most part, synths and samplers come with their own in built LFO's which you can assign to various parameters so that you can modulate these things at a rate & depth set by you. There are also a load of 3rd party midi LFO's that are available too that usually have a lot more features than standard device LFO's. For example: https://www.xferrecords.com/products/lfotool
My favourite: http://www.cableguys.com/midi-shaper.html
Have a look on http://www.kvraudio.com/plugins/windows ... st-popular
under the free section, you may have to define your search criteria.
If you use Max For Live, there's a device called steplocker, ( http://fabriziopoce.com/steplocker.html
) I've just got this as it has a step locking feature which reminded me of my old Elektron Machinedrum and the way I sequenced on that. I haven't tried this out properly yet but might be something to look at.
That said, you can't beat clip envelopes.