I get lots of questions so hopefully the pics will give the answers. Like I said, I'll lend my career to any of you guys.
The pics are of a sub-enclosure and while the thread probably belongs mostly in the audio forum, there are a lot of you doing fiberglass fabrication in the interior section and a sub enclosure is an interior item. If you have questions, feel free to PM.
Basic skeleton. The concept of the skeleton is primary for fiberglass sub enclosures. Its also a technique that can be used for interior items like the screen install I showed you all or doing other odds and ends like center consoles. This can also be accomplished by using high density foam and carving it to the desired shape and then glassing over it.
Pic 2 & 3:
Using a strechy material pulled extremely tight (I emphasize tight) over the skeleton and staple gun it to the work bench and not to the item. You'll cut the access off latter only after all layers of fiberglass are laid. Strechy material is only for form and shoulf not be relied on for ANY structural intergrity to any fiberglassing project. And, should always be followed up with several layers of glass.
Lather the resin onto the strechy material. you may have to work in sections by making several batches of resin. Work in sections to avoid making one large resin batch. Making a large resin batch will likely result in Cook-Off or spontaneous curing of the resin and greatly reduce your work time and ruin good resin. If you know that an area will be removed later and never make contact with a surface below it like in the case of the center woofer rings, don't waste your resin covering those areas.
Pic 5 & 6:
Size your sheet of fiberglass to allow over hang. The over hung area will be trimmed off. In this pic you'll see the fiberglass used IS WEAVE OR CLOTH.
Don't get this mistaken. Cloth looks like tweed and matte looks like spagetti mashed together. The knit of the cloth fiberglass is excellent for curves as the threading knit will expand or contract to a degree around curves much better than matte. The lighter the fiberglass, the better the conformity but the more layers required. The fiberglass you see here is from Wicks (See thread labeled: Fiberglass Supply Resource). This glass is a heavy 12 oz glass but its aircraft grade (Yes there is a difference) which makes it really soft and extremely forgiving on curves (Remember, you don't see many square airplanes). The heavy weight glas chosen allows for less layers needed to achieve structural integrity.
Trim access off using a cut off wheel or razor. When using a cut off wheel, be careful of glass or material not hard from resin. It could get spun up in the wheel. Then use a drum sander for a die grinder or dremel and sand up to the edge of the skeleton to give nice crisp lines.
Bondo time. Work the area in bondo in sections. this allows for better handling of the bondo and quick sanding during its cure to eliminate hours of sanding. The purpose here is to fill the valleys and create a smooth and uniform surface.
DONT be afraid to write on your part. Look yopur part over very carefully and circle areas needing attention. Use terms like "Fill" or "Build-Up", or "Sand" if you need it in the area noted. A trick: turn the light off in your work area but leave a source of ambient light to one end of your part. Then look over the part at a shallow angle in the direction of the light source. The ambient light source will quickly reveal shadows which are your areas of "Valley". Then use a marker and mark the appriopriate term for correcting the area by either sanding or building up the area with more bondo.
Using a GREY filler primer (not black), spray your item. this may take several times but, after each coat, notice the pin hole that is characteristic with bondo and fill them with glaze putty. Be sure to sand the primer with 400 grit of better between coats.
Partcle board, fiberglass, bondo, all add weight to the item. Depending on the size of the item the weight and bulkiness of the item maybe unmanageable. Get help to install your item if needed. This pic shows the sub enclosure installed (not permanently). It still needs to be painted and cleared.
These pics should give you a general understanding of the processes involved with fiberglassing. Be mindful of the fact that fiberglassing will require excessive amounts of sanding. For example, this enclosure too both saturday and sunday, 8 hours each day to sand and get level. Surface prep is everything when painting a part. Take your time with the surface prep and get it right so you don't ruin a good paint job.
PM me if you guys have any further questions. I should have it painted next weekend with the gunmetal color like in the screen install and the amp area on top will be lined with grphite formica and a framed cover will be installed over the amps like your home speakers and their fabric covered frame over them.