Make the cake: Position racks in the upper and lower thirds of the oven and preheat to 350 degrees F. Coat two 9-inch round cake pans and two 6-inch round cake pans with cooking spray; dust with flour and tap out the excess. Line the bottom of each pan with parchment.
Whisk the flour, granulated sugar, cocoa powder, baking powder, baking soda and salt in a large bowl. Stir in the milk, vegetable oil and eggs. Mix with a rubber spatula until just combined. Stir in the vanilla and coffee extracts.
Pour 3 cups batter into each of the prepared 9-inch pans. Divide the remaining batter between the 6-inch pans (about 11/2 cups each); tap the pans against the counter to release any air bubbles. Bake, switching the position of the pans halfway through, until a toothpick inserted into the center of the cakes comes out clean, about 35 minutes for the 6-inch cakes and 45 minutes for the 9-inch cakes. Transfer to racks and let cool 10 minutes in the pans, then remove the cakes to the racks, discard the parchment and let cool completely.
Using a long serrated knife, split the cake layers in half horizontally to create four 9-inch layers and four 6-inch layers.
Whisk the coconut milk and sweetened condensed milk in a medium bowl. Brush onto the cooled cake layers, using just enough to moisten the top of each.
Make the frosting: Puree the raspberries in a food processor until smooth. Beat the butter in a large bowl with a mixer on medium-high speed until smooth, about 1 minute. Slowly beat in 4 cups confectioners? sugar until smooth. Add the raspberry puree, the remaining 2 cups confectioners? sugar and the lemon zest and juice; beat until fluffy, about 2 more minutes.
Assemble the cake: Place one 9-inch layer on a cardboard round. Using an offset spatula, spread about 3/4 cup frosting on top. Stack the remaining 9-inch cake layers on top, spreading 3/4 cup frosting between each. Cover the top and sides of the cake with a thin layer of frosting (this is the crumb coat). Refrigerate until set, at least 30 minutes.
Make the fondant: Dust a surface with confectioners? sugar. Roll 8 ounces white fondant into a thick log. Roll 2 ounces each blue, pink, green and yellow fondant (or other desired colors) into thin logs the same length as the white log. Use a little water to stick the colored logs to the white log. Use your hands to roll the fondant logs together into one big log, then twist the log a few times. Fold the twisted fondant log in half, then gather together into a ball. Using a rolling pin, roll out the fondant ball into a 15-inch round, about 1/8 inch thick, dusting with confectioners? sugar as needed. Lift the round of marbled fondant and drape it over the 6-inch cake. Smooth out the fondant with your hands. Trim off the excess fondant around the cake with a paring knife. Refrigerate until ready to assemble. Place the 9-inch layer cake on a cake board or cake stand; top with the 6-inch layer cake. Pipe the reserved frosting around the bottom edges of each cake layer. Repeat steps 1 through 3 to make a larger ball of marbled fondant, using 1 pound white fondant and 4 ounces each of the colored fondants. Roll into an 18-inch round. Drape the fondant over the 9-inch cake, then smooth and trim the edges.
Meanwhile, lay one 6-inch cake layer on a cardboard round; spread 1/4 cup frosting on top. Stack the remaining 6-inch layers on top, spreading 1/4 cup frosting between each. Cover the top and sides of the cake with a thin layer of frosting. Refrigerate at least 30 minutes. Place the remaining frosting in a pastry bag fitted with a star tip; set aside.
Cover the tiers with marbled fondant and finish assembling. Decorate with the remaining frosting as desired. Refrigerate until ready to serve.