I used a trim router, cove routing bit, and saw horses (no router table) and cut this to edge my display shelf. You could easily adapt it for a display stand. Cut a square piece of wood,route all four sides, drill the appropriate size hole and glue in a dowel. Easy peasy.
You could use two different sizes of squares and different edges. Only limited by your imagination.
Since there is nothing on the market for MMX models, I made a fast and cheap display stand for MMX:
Cereal box cardboard, 1/4" dowel, and glue.
But for most rockets, I use either the plastic Estes or fiberboard Qualmann's display stands.
Semroc makes plywood stands in 24 and 29mm. For these bigger rockets I find the legs of the fiber stands can slowly bend and distort, toppling the rocket over.
And while I have the tools to make my own display stands, I find my time is more productively used in building rockets rather than woodworking. Personal choice.
Sidebar: have you ever noticed that 13, 18, 24, and 29mm engine casings can nest into each other? So if you don't have an Estes 24mm display stand you can take an expended engine casing and convert an 18mm stand into a 24mm one. Bonus is that it can also accommodate the engine hook, while the 24mm one will have it pushed out.
l to r: 13,18, and 24mm Estes stands with 18,24, and 29mm "adapters", Semroc 29mm, Qualmann 29mm