I've been using GIMP as a free alternative to Photoshop (it's not nearly as good, but it's good enough). HumbleBundle.com sells video game dev tools on occasion, and I've gotten some good royalty free loop packs and basic audio editing software for a few dollars there. Fusion 360 or SketchUp are good free cad programs.

i use
inkscape: free, 2D Vector based graphic tool
krita: free, photoshop alternative
tinkercad.com: free, online based, basic 3d design
wave-editor: free, sound editor

https://freesound.org/ : sound effects

I would recommend: https://missionpinball.org/ (Disclaimer: I am one of the maintainers). We recently started a collections of CAD designs here: https://hardware.missionpinball.org/. Another good resource is: http://pinballmakers.com/.

I also started a Youtube channel with some videos about building custom pimballs: https://m.youtube.com/channel/UCPXS1guuUIyC49ysa-nRuzg. I also stream on twitch: http://twitch.tv/jabdoa.

Jan

I have found fusion 360 incredibly useful for homebrew Design. I use it for all of my 3D printed parts and CNC router tool path. I believe you can still use it as a hobbyist for free. The learning curve is not in substantial but there are good videos.

I use Adobe creative cloud for the rest. Graphics were done in a combination of Photoshop, adobe illustrator and on the iPad adobe draw. Animations I did in after effects and premier pro.

Yes you can use it as enthusiast, then it is officially free.

I've tried just about every photoshop clone, and nothing beats the original (or maybe I'm just so used to the interface I find myself fumbling in other programs). I was able to find a used copy of CS5 for a decent price

I use solidworks for my job (have been for 15 years), and although fusion 360 is very close.. again, I'm used to the interface. I think either CAD program is great for designing. In fact fusion360 might have somewhat of an advantage since it has a very good CNC section built in (depending on whether you're going to cut your own playfield or farm it out). One disadvantage to using fusion360 is most of the 3D files on pinballmakers is solidworks, and unless you have a professional version of fusion360 you can't import those models. I do know that a homebrew twitch streamer that goes by Surreal_7 is building a giant library of stock parts in fusion360. I asked him if he ever considered sharing the files and he said he thought about it.

Everybody should know about the creative commons non-commercial license. It lets you freely distribute your IP without allowing potential competitors to copy the IP for profit. It lets the community benefit, while still preserving your competitive edge, in a business sense. Though, frankly, everybody steals ideas from everybody else in pinball :p

deleted. I hit a wrong button :p