does anyone one know what is mexician paste I found it in a cake magazine.

I think what it is refering to is Pastillage. It is very similar to gumpaste.
Here is a recipe:

Pastillage

1 package of plain gelatin
1/2 c water
1 t cream of tartar
5 c powdered sugar
1 c cornstarch

Sift the powdered sugar and cornstarch together. In a small saucepan, place water and cream of tartar in, then sprinkle the plain gelatin over the top. Stir over low heat until dissolved. There may be an amount of cream of tartar that doesn't dissolve, just be sure no amount of gelatin is left undissolved. Remove from heat and add to bowl of stand up mixer, like a Kitchen-Aid. Put on a paddle attachment and with low speed, add in the dry ingredients mixing spoonful by mixing spoonful (couple of tablespoons at a time or so) at a time. When all is incorporated, switch to medium speed until mixture is lightened and very white, about 3 minutes. Remove from bowl, wrap in plastic wrap and let sit for half an hour before rolling out. Can be frozen; place in refrigerator overnight to thaw. Roll out with cornstarch.

Hi, Mexican paste is similar to gumpaste. It is more softer than gumpaste. But its not Pastillage. Pastillage dries really hard. I have used this paste to make the back wings in my Blue Plane.

If you have Patchwork cutters, this is the paste they recommend you to use. Here is the link from there site on how to make it,

http://www.patchworkcutters.co.uk/POM/pom_mexican1.asp

HTH.