So, I'm very, very new to all of this. Pardon the mess in the picture.

I'm  trying to figure out the best (or even good) way to add flanges to this fender in order to get a smooth surface on the mold. The shape is pretty complex (for me, at least). I've tried layers of masking tape, HVAC aluminum tape, corrugated plastic sign board - very difficult to fit to this shape, especially in the section in the bottom-left part of this picture - and some other stuff I can't remember.

Aluminum tape is the easiest to work with as it molds nicely and sticks to the part without jumping through hoops. However, it has a very anti-smooth surface. The resulting mold is something that I feel won't seal well for bagging.

Any suggestions?  Somebody  elsewhere mentioned using foam blocks, but I'm not sure how to implement that.




Also, since I can't find the "edit" button: I'm happy to trim the part when it comes out of the mold. The "top" of the fender, in the bottom-left of the picture, has a shape like

```\___/```\___/```

(pardon ASCII art). Cutting out the fjords after demolding is perfectly acceptable.


I'm sure I'm over-thinking this.

Corrugated plastic sign board is great for this, I think you should give it another go. It is very flexible perpendicular to the corrugations, so when cutting it just make sure you cut your flanges in the flexible direction of the board. For even more flexibility you can score the back of the sign board without cutting through the surface. 

I'm yet to find an object I can't flange with coreflute.

That's going to add a ton of surface area to the mold, and thus increase part cost. If you look at the curved edge (bottom-right of the part in the picture, I'd have to bring that down between 3 and 4 inches to meet the board, (same thing on the other side) then out a few inches to get a usable flange. When I switch from glass to carbon (once I get a good mold and work the kinks out of the bagging / infusion process) the additional material cost will add up quickly. I'm sure how well infusion is going to work if the laminate doesn't extend to the flange. (But, again, I'm new at this so I may just be over-thinking things.)

I realize  the picture is bad. The the profile of the part resembles a lofted arch with an offset apex, and nearly-vertical sides.

I should have paid more attention in art class. :|

**Hmm

It just occurred to me that I could use the HVAC tape as a support for the signboard. That should give me the flexiblity / mold-ability that I'm looking for with this shape, as well as a smooth resin-friendly surface. Worth a shot, but I still feel that I'm going about this in a very suboptimal fashion.

OR, I could  put the thing down on a board, cut some foam to fill in the arches and extend out parallel to the board surface to provide a flat-ish surface for the flange. That should be cheap and easy.

This stuff has a pretty long learning curve! Thanks everyone for the help.