The 36-year-old played more than 340 games for Dons during two spells at the club, most recently from 2010-17, when he departed for Millwall.
Following three seasons with the Hammers though, Martin was released at the end of last season, and began training with Lewis Price’s goalkeeping unit for a few weeks.
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Though there is no view to bring the keeper back on a permanent basis, head coach Manning said Martin’s involvement with the group has been a good thing.
“He's been terrific,” he said. “We had here for him to keep ticking over, to keep football-fit, to stay sharp. Since coming into training with us, he's looked sharp too and looked progressively better too in the small-sided games and finishing drills.
“He's a terrific character, he's been great with the group in the short time he's been with us. He's done really well.”