My husband and I found the design on the internet as my son wanted a firetruck for his 4th birthday. We used chocolate cake - 8 to be exact. There was a little wastage after we cut the shape out... we then spread with Nutella to hold the icing on.
I kneaded a little white icing with the red to dull it a little and used already made black icing. We first put the red on and smoothed, then the strip of black. For all the accessory bits like the signs on the side, the side compartments, the bull-bar, the front grill and the ladder (which was the hardest bit), I made a couple of days prior so they would harden a little.
With the silver, I bought a bottle of edible paint. The windows I made when I iced the whole cake. For the base I used a cake board and bought 2 cheap tractors from Go-Lo, removed the wheels, remounted them on metal skewers and sticky taped them to the base.
For the fire hydrant I used two pieces of cake cut into circles and glued together with Nutella as well as around the edges. I then rolled out my red icing an rolled it around the pieces of cake. For the top of it I rolled a circle shape and laid it over the top. With a separate piece of icing I rolled it into a worm and placed it around the bottom of the lid. Then I indented the marks as desired, placed a pea-like shape on top and painted the lid silver.
Around the very base I rolled another worm like shape and placed that around the base and moulded it in. I then rolled 2 pea-shaped red pieces of icing, placed them in desired spots and softly pressed them flat with a rounded plastic instrument. Then do the same process but smaller to place on the top of the bigger ones (but do not press in, leave as balls) and paint those balls silver.
For the hose I just rolled out as a worm some white to desired length, pressed around the end, pinched it a little and painted it silver. For the water I kneaded white with blue coloring (of course it's water) and rolled it out to desired shape. Then made little water droplets coming out of the hose into the water. I then took white icing and shaped my sons name and how old he turned. That was a little fiddly so I think next time I'll do a plaque like thing with icing (that you don't even eat) I would pipe icing the name.
This homemade fire truck birthday cake took many hours and a very sore back but well worth it when I saw my son's face.