Step 1: Tools and Materials
A baby jumper (onesie, bodysuit, creeper, etc.) In a solid color like a star trek uniform.
The Star Trek symbol
A Baby (Not pictured)
Step 2: Print Out (Or Draw) the Symbol
Since I lacked a working printer, I had my particularly artistic partner draw this for me. He took his task very seriously, and ended up drawing on paper that was too thick for my purposes. So in the end traced it onto thinner paper.
It'd be much simpler if you have a printer just to print it out. You can find many such symbols online using a brief Google search.
Step 3: Prep the Symbol
For those of you who, like me, had to draw the symbol out, you could color it at this time or you could wait till later. I had some trouble with my iron bleaching the colors so in the end I had to color of later.
For those printing out the symbol cut the symbol out and to glue it to a similarly sized bit of freezer paper. Make sure you glue it's to the mat side of the paper not the shiny side. Then trim the freezer paper to fit the symbol.
Step 4: Attach to the Creeper
Place the symbol about where you'd want it on the jumpsuit and then lay a hot iron on top of it for no more than 20 or 30 seconds. This should be enough to adhere it to the fabric. If not try it again for a little longer.
(If your baby is a little grabber like mine and you don't mind sacrificing the outfit for the purpose of a costume, you can always glue it on.)
If your iron leached colors, or you have not colored the symbol yet, go ahead and do it now.
Step 5: Place Costume on Baby and Display
Place your baby inside the onesie and show off your wonderful cheap and easy baby costume!
You can change around the order of the steps, but just make sure you do the ironing before placing baby in the costume. That's how we lost our prototype model.