Short form, no legit ways. The old Macross-inspired Marauder ain't a mini no more.
Nor do we encourage discussions on non-legit items on CGL's official site.
In terms of legit, you could track down an old mini on ePay and hack it up, but that would just leave you with the same problem one step on.
Gashapon (Japanese bubblegum machine toys) may work, or be too small. RoboTech Tactics Glaug pods are another source, but you may have to cut down their plastic legs to suit.
For really outre sources - track down MFUK Katyusha or Catapult K2 minis, but they're also OOP and rare. The legs share components with the old Unseen mini.
W.