I am going to start building a center console within the next couple days. I plan on making the base out of fiberglass, (resin over 3m tape to get exact shape of floor,) mdf sides, and fiberglass top. Now my questions are . . .
1.) How would I fill the gap between the tape/resin floor and straight mfd sides, or would I have to cut the wood sides to line up perfectly with the floor?
2.) On top of the console, would you suggest using like a t-shirt material or fleece as a starting point, or just mdf instead of fiberglass since it's going to be a smooth, straight, flat surface?
It's going in an S-10 and it will be less than a foot wide, just kind of long. Here's the curveball though. I am going to somehow mold in a plastic piece off of a stock console that has two cupholders, and a storage space, which is actually going to hold an air guage and a few switches. How would I go about doing this? and would it be easier to do it using glass or just an mdf top with some epoxy to fill in the gaps? Either way, how would I mount that piece where I wanted it?

To join the MDF sides and the fiberglass base, my choice would be Duraglas. The trick to ensure a solid bond between the MDF and Duraglas is to brush resin on the MDF before applying the Duraglas. You don't have to re-resin the base because Duraglas sticks fine to resin. You can see some pics of proof here...
Painting over joints in MDF

The gap between the MDF and base doesn't need to be perfect, but should be within 1/4" to 1/2". Here's a pic of a sub enclosure with the MDF sides attached with Duraglas.



Make sure to lay up your fiberglass base several inches larger than where you expect the sides of the console to contact the base. Another thing that I prefer to do is to apply heavy duty aluminum foil over the masking tape with 3M Super 77 spray glue. Use a bondo spreader to smooth the wrinkles in the foil. You can also wax over the foil. The foil keeps the masking tape from getting super sticky from the resin/heat. Use compressed air to help remove the foil from the base after everything is cured. If you haven't done too much fiberglass work, follow this mixing chart for the resin. This chart is for 75 degrees F, so if it's hotter, use a little less catalyst.



If the top of the console is going to be flat, just use MDF. There usually isn't any point in making flat parts with fiberglass unless the part needs to be waterproof or lighter than MDF. Cut the side pieces and the top, dry fit them (screw together without glue) to make sure everything fits. Use CA glue or a little bit of Duraglas/Bondo (like tack welds) to first attach the sides to the base, so things don't move around when you are applying the full spread of Duraglas. Make sure to tape off any big gaps between the base and side with masking tape so the Duraglas doesn't just ooze out the other side.

How to attach the cupholder part to your console, depends on a lot of factors. It will probably involve stretching some material, resin, mat, Duraglas, and filler. Pictures will help. You should also think about what you plan on covering/finishing the console with before you start because that will determine where the "break lines" should be. Good luck!

if u look at those pictures, imagine the cupholders and storage part only. the part where the shifter goes is cut off. that will be towards the top of my console, which will go just about all the way up to where the ashtray is.

This is my design.

Just make your own storage pocket and go to a boat store/supply store and get some cup holders. They are cheap. Just cut the appropriate holes and drop them in.

cup holders would be easy, but i don't just want a square storage compartment. i like how this one has a curve, and a rubber piece that fits in it perfectly. i guess i could cut around the compartment on the plastic, trace it onto the wood, then cut it and drop it in. same with the cupholders. hmmm, i may have to change this around again. oh, and the sides will be suede wrapped, and vinyl wrapped on top

Well, there are plenty of threads that show plastic being blended into a project. Pretty simple really.
Just build the console how you want it, set the plastic part where you want it on top, trim it open so the peice fit in snug, use some CA to hold it in place and then use an epoxy or urethane to bond the 2 parts together.
I like Maxim by Evercoat myself. There is also SEM, Lord Fusor, 3M/Duramix.

Hey Jon!

So you've been liking the Maxim stuff? Is it holding up well over time?

You got me hooked on it too! Good stuff & it sands very easy

Definatly.
I have not had any issues with it.
At the auto auction I do interior repairs at now, I got them to try it out after seeing them fight some 3M stuff. They all use it now also.

Which epoxies are you using exactly? I saw that Maxim is the name of the whole line of products...