Sorry but I don't understand what you meen with 2.5D
I know that the cost X Performance of the block will not be equal to the tc-4 but i whant to build on, you know just for see!!!
My idea was that i'm thinking on building a cnc routter and use it to do some of casemod (cut the case, make draws on the acrilic, and if possible make a watterblock)
Do you think that is to dificult to do a wb like the wb from the site that i've told you? The desing is verry simple.
Note: I'm a complete newbie in cnc and cad.
RE-edited
I've found one more pic of the wb (just the base)