download noitatool.7z, and put the folder contained in it into your noita mods directory (rightclick noita in steam -> manage -> browse local files -> mods)
for the seed changer to work, you need to enable the associated mod inside the game's mod settings. if something here is malfunctioning, sometimes disabling other seed changers might do the trick.
the tool can be used by doubleclicking noitatool.cmd, adding a shortcut to it on your desktop or in steam (add a non-steam game -> browse -> type in %windir%\system32\cmd.exe -> set launch args as "/c \path\to\noitatool.cmd"), or through the command line (if you can manage to resize your window right)
i did this mostly as a very simple exercise in batch scripting, and most of the code i used is borrowed from elsewhere.
i have tried my hardest to bend the code so that it works nicely together as one package, but many issues may arise from this, and the end result is very spaghetti-y indeed.
feel free to tinker with it though, and share your own variations! :D
if you have issues with the tool or ideas to possibly implement, please tell me about it on the reddit thread or on twitter at @unnifi, and i'll see what i can do.
HootzMcToke for creating NoitaSaveTool.cmd, which most of the GUI and the entire saving system is ripped from
Dregu for creating Start with custom seed.zip, which the seed editor is based on
also, literally countless stackoverflow and superuser threads for teaching me the basics of the batch script, and Arska for helping me test the damn thing.