OPMs will be hoping to cap a memorable season by adding the Devon Junior Shield to the Counties Three Devon East title they have already won.
The Old Boys visit league rivals Torrington on Saturday for the county final.
They will be big favourites to lift the cup, having won the league while Torrington finished second-from-bottom.
However, Torrington have home advantage in the final and they have proved difficult to beat Donnacroft Field.
Last week, Torrington beat 14-man Techs 19-17 in the semi-finals, while they pushed OPMs close in terrible conditions at the start of January, narrowly losing 11-8. However, OPMs did beat them 48-0 at home earlier in the season.
Counties Three Devon West champions Plymouth Argaum should have been playing Dartmouth away in the Devon Junior Bowl final this weekend, but that match has been postponed as Dartmouth have a national Papa John’s Community Cup quarter-final.
Meanwhile, Counties Two Devon champions Tavistock, fresh from winning the Lockie Cup on Wednesday night, will be looking to reach another cup final when they host Torquay Athletic in the semi-finals of the Devon Junior Cup at Sandy Park on Saturday.
Torquay finished as runners-up in the league behind Tavistock and did give them two good games in the league, including a tight 8-7 contest in horrible weather at Sandy Park in January, which was the closest Tavistock have come to losing at home this season.
After already lifting the league title and Lockie Cup, Tavistock would like to make it three trophies.
“We might as well try and get a hat-trick,” said head coach Joe Caddy.
“But Torquay have given us some fairly tough games and they have got some good players.”
Tavistock do have to make a number of changes to the side that beat Devonport Services II in the Lockie Cup final on Wednesday.
Second-rowers Charlie Brown and Seb Cox are both missing, as is try-scorer Jake Le Gassick, who injured his knee.
Scrum-half George Hillson is also still missing, while Tavistock do switch around their back-row after a physical mid-week fixture.
Andrew Schuttkacker, Dan Yateman, Richard Cann, Jack Giddy, Jack Easton and Dan Redstone are among those coming into the starting line-up from Wednesday.
“We are now down to possibly the last two games of the season and then everyone can have a rest for a few weeks before pre-season starts,” said Caddy.
The Peninsula Medical School have pulled out of a RNEC Cup semi-final against Plymstock Albion Oaks II on Saturday. That means Oaks II will play Saltash in the final on Wednesday.
Saltash’s second team play in the final of the Duchy Shield on Saturday. They take on their St Ives counterparts at Falmouth, while Saltash’s first team are due to play Bodmin in the semi-final of the Cornwall Clubs’ Cup.