After training for an hour, the players then signed autographs and posed for photographs with the fans present. Head coach Joe Schmidt enjoyed the feel-good factor and the warm weather.
"To be honest everyday is an open day for us because our training sessions are open to anyone," admitted Schmidt, referring to their regular run-outs in UCD.
"To make it an official open day is great because every open day we have had we have had really good weather. I'd be delighted if people came if we got this type of weather every time!"
Flanker Shane Jennings successfully came through his first appearance in two months when he featured in Saturday night's 34-26 Magners League victory over Ulster in the RDS.
He trained with the rest of the squad on Tuesday along with Gordon D'Arcy and Brian O'Driscoll, who both missed the interprovincial clash due to minor niggles.
It is expected that both D'Arcy and O'Driscoll should be available for selection for Saturday afternoon's encounter with Aironi Rugby. There are no fresh injury concerns for the province.
Shane Horgan has now scored seven tries in 14 Magners League appearances so far this season.
Cian Healy's next appearance will be his 75th for the province, while fellow prop Heinke van der Merwe scored his first Leinster try when winning his 26th cap against Ulster.
Meanwhile, the knocks sustained by Leo Cullen and Kevin McLaughlin in the second half of last Saturday's game are not thought to be serious and both should be in contention to face Aironi.
Commenting on Saturday's opponents, Schmidt added: "It's a banana skin, Aironi. The danger with there being 50 competition points between us in the table is that there is a little bit of complacency.
"We have trained hard and that is testament to what we believe is going to be a tough test.
"When we played them here in February, they took a five-metre tap penalty at one stage that could have made it 16-16 and the guy knocked it on.
"We managed to get down the other end and score a try but they came away from here with a losing bonus point. They have seven losing bonus points, three games at home they have lost by a point. So, while they have a solitary win they haven't been far away very often."