I started playing the Stone Hearth not just a few days ago, and I got really interested in the game. And today I found out that this game can be modded, so I wanna try making a mod.
The problem is though… I can do a little programming and make sprites and such, but I heard that you need Qubicle Voxel Editor, and not the demo version…
Do I have to buy this or is there any replacement?
I mean, except making some mods for the Stone Hearth, I don’t know if I will use that tool a lot…
Nope. If you’d like, I believe one of the more popular software used for this is called ‘MagicaVoxel’ (link here). You can generally use anything matching the terms “voxel editor”. Also, yay for modding. 
Also, if you need a reference to Lua to get started, check out Programming in Lua. If you need a reference for standard Lua modules, check out the Reference Manual. If you need to peek at the Stonehearth source, you can rename “.smod” files to “.zip” and extract whatever you need. Happy hacking!
Awesome Answers! Thanks, I’ll Check it out!
I really wanna make a mod about reproduction(Birth, Marriage, Getting Old ‘n’ stuff…)
or government ‘n’ stuff… but I still needed the Graphic Tool…
i also use magicavoxel and it works quite well for me!
but if i need to make multi-matrix things (anything requiring anims: armor, creatures, etc) then i use voxelshop, which is also free.
at the end you need both ^^ the most use magica for modelling and voxelshop for matrixnaming and positioning xD but like i have learned at the end it works but not perfect ^^ mostly wrong positions or little issues ^^
because of this i have get qb3 ^^ BUT i use it very often and im an very active member of this community 
so i would suggest only to buy it if you want to use play with stonehearth for some time or for other voxelbased games ^^