To make something, ( a process, a procedure, a task or a design) much more difficult than is necessary by adding multiple, redundant steps or complexity. In the case of a design, to make something really ugly.
This wiring was definitely put in by a buncle.
Who made this nasty looking website, uncle buncle?
Jeez, this damn form is so bloody complicated. Has it been buncled?
Who made this road junction, the buncalator?
Man, I need to justify charging more money for this. I think I need to bunclify it.