Glad it worked out ok.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I eased the corner problem by inserting plasticene smoothed to a 3mm radius using an old credit card and, with 200g 2x2 twill fibreglass cut on the bias, the 2 holders that I need came out just fine as attached photo illustrates.  Your help much appreciated, Warren.

Thankyou, Warren.  I'll have a go with glass first.

Glass is fine, but carbon will be stiffer for the same thickness.

1mm thickness is generally 4 layers of 200g carbon cloth which is about 0.25mm thick.  Look at the specifications of other cloths for thier thickness and you can calculate how many layers you will need to achieve a set thickness.

Allow the first layer of resin to go tacky, then apply the first cloth layer and it will stick in place making it easier to get into the corners.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I need to make a holder for a flexible (engine) air filter.  The holder is an oval ring about 200mm x 120mm and 20mm deep.    The section of the holder is a channel 20mm x 10mm with the open side pointing inwards and the material thickness wants to be about 1mm.  The internal corners want to be reasonably sharp, say less than 4mm radius.  The external corners don't matter.  There are no particular stress requirements but the holder needs to be reasonably robust since inserting the zig-zag wire-mesh & cloth filter requires some manipulation.  I've made a mould with a removable faceplate but am at a loss as to what weight or type of reinforcement to use. 

As a novice in such matters, my starting point is to use 4 or 5 layers of fibreglass tissue in shortish lengths to minimise crinkling up the sides.  And to use EL2 resin in order to accommodate the amount of time required to lay.  But I suspect that this would be a bit flimsy. 

Would a few layers of a light cloth lie adequately into the corners and not require extensive cutting to avoid crinkling up the sides?  Is there a suitable carbon-fibre reinforcement that would be better than glass?

I would greatly appreciate any assistance.