Not really. This might give you a guide on fibreglassing.
Cars - JOE250.com
If you aren't keen on fibreglass, then body putty is easy to use (and you can actually get fibreglass reenforced putty which is stronger, although I haven't used it).
The most important thing is to attach the cups together strongly and align them correctly. Once you have the basic frame, adding filler is easy. Don't rush anything, as small mistakes early on usually turn into big headaches later.
I simply got the standard mounting cups and glued them together. If you plan on using sunshades on your gauges, you will probably need them spaced out a little to fit. I did this with a bit of metal in between and a good amount of epoxy glue.
(This is a finished pic, but it shows what I mean by the spacing)
Make sure that they are aligned properly before gluing. If you sit them on the dash where you want them to go, make sure they all point at your head, not up or down, or to either side (a small miss-alignment now will be much more obvious later on, particularly if you use covers over the gauges and/or gauges with illuminated rings like the prosport 'halo' series). Maybe even wire up the gauges and put them in to make sure that you are 100% happy with the look before going any further
I rushed this a bit and they didn't end up properly aligned. If I redo it, I'll probably attach them with small bolts instead, then they could be easily adjusted until they are perfect.
I then popped out the air vent and drilled through it (on the left hand side). Attached it to the bottom of the middle gauge with a small bolt and lots of glue. Again, proper alignment is the key.
Once they are all aligned and solid, you can start adding filler. Fill in the gaps between the gauges and between the gauge an the air vent. This is the creative part - just keep adding layers of filling till you get it to a shape that you like. This will likely involve filling, sanding, more filling, more sanding, but take your time and get it right. You want a perfect surface with absolutely no imperfections (I didn't first time and had to redo it).
Once you have the shape right, then it's time for painting. Pretty much follow the steps here:
How to: Paint car parts
Most of the above is from my own mistakes, so hopefully you would end up with something much cleaner than I did in the end.
Good luck
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