3880 is big project even with experience in dtg diy
there is a big differnce with a3 and a4 printer is it not standart setting
but all the logic is same
hacking pe sensor, keep asf module as is it, take siganl for pf sensor, cut epson structure, cut asf shaft, there is a few videos on youtube.
But you need to know your base need to be stable and with good size, take time to understand how all work
NB there not realy all information to build one, even UFO give almost all but there is a few info missing