Exciting thing your first build
For a working keyboard you all you need is:
PCB with controller - the controller part are small, fiddly SMD so not good for beginners to hand solder, so go with the soldered option.
Diodes - 1n4418 are the hand solderable ones so get them. The pcb has this symbol for them, -|>|- the black bar on the diode goes this side of it.
Switches - you need some
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Stabilisers - Winkeyless are 7 long, Winkey are 6.25. Most modern boards/keysets use 6.25, if you have one you're going to use measure it against the letter keys and you'll know which you want.
Case - optional, but probably a good idea...
If you're not sure which holes to put the switches in put keycaps on them and put them in the PCB, then you'll know. Most are obvious.
If you want LEDs there are two options.
The in switch LEDs (backlighting) are hand solderable, smaller than switches and diodes but you should be fine with thin solder. Again, they have to go in the right way but you can't tell which for sure until you have them in your hand to look at. Google "LED polarity" and check against the pics you find which is + then match the PCB.
The resistors are SMD though, so get them soldered.
The RGB LEDs go under the PCB to create the glow, looking at the B.87R they look to be hand solderable but they will be even harder than the in switch ones, so depending on your experience you might want to get them soldered.
Hope that helps