The Bubble 75 custom mechanical keyboard is one of my favorite custom boards. The typing sound and experience can be tweaked by playing around with the case foam, stand-offs, plate material, and plate foam combinations. I built mine with PC plate, 1 case foam, some of the stand-offs, plate foam, eva pcb foam, tape mod, GMK stabs, and holy panda switches to create a more firm typing build. The turquois blue case color wasn't as turquois as I'd originally thought, but it worked out well as you can see in the picture below. The bubble 75 is a solid value for the money with good build quality and customizability. I also bought a brass plate so the next time I open this up, I'll switch it up for a very different typing experience.
The only odd thing is that the daughter board and ribbon cables cannot be purchased separately so even if you buy an extra PCB, you will still be missing the extra db and longer ribbon cables for the rainy day. Not a show stopper by any means, but I thought it was an odd decision made by Velocifire. I'm hoping they'll make it available for purchase in the future.