The environment section doesn't do what I thought it would. Duplication is bad, but seems neccessary.

appveyor.yml

@@ -18,11 +18,6 @@ image:
 platform:
   - Win32
   - x64
-
-environment:
-  build_cache_dir: bin\.mtime_cache
-  build_binary_dir: bin\%CONFIGURATION%
-  appveyor_script_dir: scripts\AppVeyor
   
 configuration: Release
 
@@ -42,20 +37,20 @@ cache:
   - assimp_cmd.dir\%CONFIGURATION%
   - assimp_viewer.dir\%CONFIGURATION%
   - unit.dir\%CONFIGURATION%
-  - $(build_cache_dir)
+  - bin\.mtime_cache
   
 before_build:
-  - ruby %appveyor_script_dir%\mtime_cache -g %appveyor_script_dir%\cacheglobs.txt -c %build_cache_dir%\cache.json
+  - ruby scripts\AppVeyor\mtime_cache -g scripts\AppVeyor\cacheglobs.txt -c bin\.mtime_cache\cache.json
   
 build:
   parallel: true
   project: Assimp.sln
   
 after_build:
-  - 7z a assimp.7z %build_binary_dir%\* lib\%CONFIGURATION%\*
+  - 7z a assimp.7z bin\%CONFIGURATION%\* lib\%CONFIGURATION%\*
 
 test_script:
-  - cmd: %build_binary_dir%\unit.exe --gtest_output=xml:testout.xml
+  - cmd: bin\%CONFIGURATION%\unit.exe --gtest_output=xml:testout.xml
 
 after_test:
   - ps: (new-object net.webclient).UploadFile("https://ci.appveyor.com/api/testresults/junit/$($env:APPVEYOR_JOB_ID)", (Resolve-Path .\testout.xml))