Canas, the top seed and defending champion, endured a lengthy rain delay before posting a 7-5, 6-4 semifinal victory over France's Julien Boutter, the fifth seed.
El Aynaoui, the second seed, took multiple rain interruptions in stride, defeating Russia's Mikhail Youzhny, 6-3, 7-6 (7-2).
Canas and El Aynaoui will battle for the $48,850 top prize in Sunday's final.
Canas, who was forced to qualify after missing most of 2000 while recovering from surgery on his left wrist, did not drop a set in seven matches en route to winning his first career ATP title at Casablanca.
Despite having to contend with difficult weather conditions, Canas is just one win away from defending an ATP title for the first time.
During the opening week of the 2002 campaign, Canas lifted the Tata Open hardcourt event trophy at Chennai, India to double his career haul.
Last year, the 30-year-old El Aynaoui lost a close match to eventual runner-up Tommy Robredo of Spain at the Complexe Al Amal, dropping the third-set tiebreaker, 9-7.
El Aynaoui reached his first career ATP final at Casablanca in 1993. He won his third career title at Doha in January, but has yet to capture his home tournament.