Any sound generator in Reaktor can be modified to give MIDI note control over the output level. Here’s how to do it in Spacedrone:
Easy peasy. An ADSR envelope multiplies the signal going to the output. You can also use a selective note gate module instead of a vanilla gate module so only one specific note will trigger output. Adjust the attack, decay, sustain and release to taste.
Download the modded ensemble here. (oops, link was broken, should work now)
If you’re looking for an interesting way to manipulate recorded samples of Spacedrone or other audio material, try my sampler pack.
UPDATE: added pitch control too. It doesn’t work the way a normal synth would because the pitches of individual voices have a random factor but you can control the range.