BlackSheepTwoOneFour
Bondo is for bodywork on cars, not plastuic kits. So no on Bondo. Most of us use putty specially made and used for plastic kits, be it Perfect Putty, Tamiya putty, etc...
Disagree. Don't limit yourself to hobby items that only have a hobby manufacturer's name on them
Bondo Glazing and Spot Putty (Bondo Red) is an excellent seam filler for plastic models. It is a solvent putty - same as Squadron Green, Squadron White, 3M, and several others. It is the same stuff, repackaged, as Dr MicroTools red putty. It has its advantages, it is a fine grain and sands & feathers well. It is inexpensive, a 4.5 oz tube is less than the cost of a smaller tube with a hobby manufacturer's logo. It is widely available at auto supply stores (Pep Boys, Auto Zone, O'Rileys, Menards, etc.) Disadvantages include an overnight drying time, shrinkage, surface etching due to the solvent, and softening plastic if you use it to imbed noseweight then enclose the fuselage with no place for the solvent to evaporate to (ask me how I know this).
Geez Alert: Squadron came out with their first body putty 30 to 40 years ago when they found out that the California car modelers were using 'real' body putty to make their custom creations. They packaged some 'real' putty in smaller, more modeler-friendly packages at not a greater price discount. IIRC Testors also had some - a cellulose based product - that had attrocious grain and didn't sand well.
Bondo also makes a Professional Glazing & Spot Putty (Bondo White). This is a 2-part catelyzed putty. Non-solvent, you mix the hardener with the putty squeezed from the tube. Mix a quarter-sized dab of resin with a peas sized dab of hardener. You can control the working time with the amount of hardener used. Fast hardening, very fine grain, non-shrinking. Sands & feathers well. This is great for the occasions where you are on a roll and don't want to wait overnight for the solvent putty to dry. Available at the auto stores mentioned -- and I think I may have seen it at Lowes Hardware
Bondo Body Filler -- in the can is very similar to Bondo White. The benefit here is that it comes in a larger package which is great when you need more for the scratchbuild project you are working on. Grain isn't as fine as Bondo White, but it still sands & feathers well. Inexpensive. Another trade name I've seen it under is Evercoat. Definately seen in Lowes, Home Depot, & Ace hardware. I've used it for more than plastic hobby work. It also has had some applications around the house.
More esoteric stuff -- Google Buzz Budzik for his Youtube videos. He is a dentist by training and he swears by dental resin (magic pink powder & water) for filling.
Like I said, don't limit yourself to only model products which have a model manufacturer's name on them. There are many equivalent products from other disciplines. Where do you think the hobby industry came up with them -- definately not R&D on their own nickel! Keep your head on a swivel and be ready to try new things.