Blockland v0002 had built in Mission Editor and Retail had it as an add-on.
The editor now works like the add-on system, except it doesn't go in Add-Ons. The editor is in Blockland\editor.zip.
To apply the editor, go to your Blocklands shortcut, right click, click properties, then at the end of the target, put " -mod editor"
Mod didn't feature the editor.