question on sewing design in sparkle vinyl

[mimoose]

Hello! I am not an upholsterer but I do have several seats to upholster for  bikes and trikes I am building for myself.  I am looking for advice on how to handle sewing a design in glitter or sparkle vinyl.  I wrote to the places I got the fabric from, but they didnt know anything.   

I  am sewing a seat for my recumbent bicycle. originally I bought a boat seat for it, but i decided the color was way too dull, even depressing looking. so i ripped apart the seat cover cushions and used  the pieces
as a pattern.
I bought  sparkle vinyl and used the pattern where the purple and gold is and added a third color in the middle. 

the question I have is  with the middle part where the red meets the purple. I dont know whether to sew the red directly over the purple,  sewing thru two layers of vinyl and leaving ugly sewing stitches showing on the red.

or do iI cut the purple fabric  into curved strips and  sew the purple and red seams  together? making the stitch invisible but risking bigger mistakes since the design will have four lines of seams ? (purple/red
and purple/gold seam for each side.)
Also, if I do it this way, should I used piping between the seams?

I have a cheaper sewing machine, but most likely I will be sew this by hand. I dont think my machine could handle this vinyl.

Any advice would be greatly appreciated. Thanks!

[scott_san_diego]

Your best bet would be to pencil out your design on the seat where you want the seams for the different colors of materials.  Then I would bring this to an upholstery shop and let them cut the material and sew it for you. This way you will end up with nice looking seat. 
It would be really hard to sew this material by hand because the material is so thick.
Good luck.
Scott

[Darren Henry]

Ditto.

Welts (piping) would be uncomfortable and don't think you'd like the look in this application.

[Rich]

Ditto Scott
Rich

[JuneC]

3 layers of that stuff would be probably 1/4" thick!  :o  It needs to be pieced rather than appliqued.  And the design you've chosen isn't easy.  Inset curves is one of the most difficult to maneuver correctly.  Like the other guys - take your seat/design/vinyl to an upholsterer.  Anything with less torque than a heavy industrial sewing machine is going to choke on that stuff. 

June

[mimoose]

Thanks everyone for responding. I will take your advice and get estimates. (Just for clarification, the section involved was just 2 layers, not three. the gold is already pieced.)
Any idea on how much it might cost? I mean in what range?