For anyone willing to dive into modding for ZT1, here are some useful links.
All of these are stuff I constantly visit and use myself.
Zoo Tycoon: Complete Collection on AbandonWare Eric, my brother on Christ, play the goddamn game already!
Render Tools:
HENDRIX's profile on GitHub You'll find here the script for automatic render. It works for Blender 2.79.
For more info on how to run HENDRIX's auto-render script, take a look at HENDRIX's project thread on ZooTek.
Watch the VideoTuto made by HENDRIX itself on how to run the automatic render script.
NifTools for Blender 2.7 use this when porting .nif models since newer versions are no longer compatible.
Graphic Tools:
BIMP plugin for GIMP Since I'm too dumb to use the script to auto create a ZT file, I use this tool in order to create indexed graphics with a max of 256 colors.
ZTStudio by jbl Last updated in August 18th. Features include creation of ZT graphics, batch conversion, palette modification, rotations and speed rate modification.
Configuration resources:
APExp v3.2 No matter how nor why, useful for several things. Do NOT use APExp to modify previously existing items, just to create new ones.
Visit GoosiferIO profile on GitHub where you'll find PANDA and EMU latest versions.
ZooBerry Docs contains a fully detailed tutorial about how to start modding. Includes MORE web resources and external links.