Hi, I have ordered in the past from JLC3dp[1] both metal printed parts and aluminum anodized CNC machined parts. I was happy with the quality and the pricing was a lot better than my local CNC companies.
Start from investing every month set amount of money into ETFs.
As you are from Europe, one of the best to start, would be Vanguard FTSE All-World ETF, or in short WVCE. I am mostly investing into it for my retirement.
If you want to feel the market more, you can buy some individual stocks, starting from blue chip ones, or if you want to gamble a bit more, you can take a look at crypto or small cap stocks.
As for platforms/brokers, there are couple of most popular in Europe: Degiro or IBKR. I myself use IBKR for stocks and ETFs.
I would pick AMD Ryzen CPU and any Nvidia GPU with more ram.
If budget allows, I would pick RTX3090, if budget is too tight, look at RTX3080 or RTX3080Ti 12 Gb vram models. 10 gb vram models can be too small in the future or if you plan to use it for image processing.
I also am working mainly with image processing and segmentation, we mainly use RTX3080 and RTX3080Ti GPUs.
It should also be cheaper to pick components and build PC yourself.