Trevor Muirhead and Neil McKenzie denied the charges against them.
The case centred on five suspicious packages; two of them addressed to Celtic manager Neil Lennon.
None of the devices were viable, but prosecutors argued that both men believed four of them were.
The first package was sent to Lennon at Glasgow's Celtic Park on the 4th of March last year.
The "hoax nail bomb" came shortly after a confrontation between the Celtic manager and Rangers FC manager Ally McCoist.
When police searched his home they found petrol cans, black wire and a bottle of cream peroxide, as well as an "oath of allegiance" to the Scottish Unionist Association, a Union flag and two flags featuring the Red Hand of Ulster.
McKenzie admitted to police that he had constructed a "hoax bomb" and said he had bought materials for other packages.
He said he was aware of how to make a bomb after seeing it on the 1980s TV show The A-Team.
Trevor Muirhead and Neil McKenzie have been found guilty of conspiring to assault Celtic manager Neil Lennon, and other high profile supporters of the club, in a parcel bomb plot.
Muirhead and McKenzie sent devices they believed were capable of exploding to Lennon, former MSP Trish Godman, the late Paul McBride QC, and an republican organisation called Cairde Na hEireann (Friends of Ireland).
44-year-old Muirhead and 42-year-old McKenzie both from Ayrshire, were originally accused of conspiring to murder their targets but the charge was thrown out yesterday due to insufficient evidence.
Trevor Muirhead and Neil McKenzie have been convicted of conspiring to assault Celtic manager Neil Lennon and other high-profile supporters of the club in a parcel bomb plot at the High Court in Glasgow.