Creating generic NPCs as a DM (DnD 3.5)

I'm fairly new to both DnD and being a DM and one of the things I struggle with is managing all the skills and stats of the NPC opponents my group encounters. I want to be able to throw opponents instantly into the game AND utilise the cool roll templates in roll20 - without having to scroll desperately through impenetrable walls of texts in my source books trying work out how some basic mechanic works whilst my group is sitting waiting.  Currently I have a complicated spreadsheet where I can choose drop downs to select race/class/level/HD and it generates a roll template I can then copy and paste into my roll20 game.   Ideally I would like to have a set of instant NPCs in my vault which I can import into my game and set to different race, levels or HD on the fly.  Is there a way of creating custom NPC character sheets to do this? Or rather, a way of instantly generating NPC character sheets during a game session, based on a database of NPC tables? Thanks in advance for any advice you can give :) 

This could be done with an API script. &nbsp;I was thinking there was one that did something similar, but I couldn't spot it in a quick look. &nbsp;Did run across this one though, which might help:&nbsp; <a href="https://app.roll20.net/forum/post/2657434/slug%7D" rel="nofollow">https://app.roll20.net/forum/post/2657434/slug%7D</a>

Ooh that looks just like what I was thinking of. Well have a read, thank you!&nbsp;