Richard asked how he make an sample-based instrument and not a sample loop.
One example from the past are JD 800.
168 are the default numbers in renoise and this is one cycle at C-4.
So go to the sample editor and push create button then take the pencil tool and paint your one sample.
Take a look to renoise instruments to understand how compose filters,envelops,etc.
Sure you can play more than one sample together.
Also you can find a collection of waveforms here http://www.adventurekid.se/akrt/waveforms/adventure-kid-waveforms/
Here are a tb sound TB 303 Renoise emulator
Is not perfect but i will try to make it better.
Renoise 3 are fuckin great for this job.