We are hosting my son's 9th birthday at our local aquatic center. He asked today to have his cake have the following things;

Kids on innertubes on the "lazy river" like the center has. Got that covered going to try a Wilson method I found.

The lazy river which is simple decorating got that covered.

Last thing was a spiral slide like the center has. Totally at a loss how to construct i. Pretty sure I am using gumpaste for the slide, royal icing over wooden skewers for supporting the slide and attaching to the cake. What could I use for a form? Am erroring on side of caution and telling my son the spiral slide is probably not going to happen. He suggested RKT for the slide. Since my guest list already includes over 2 dozen kids and adults(not counting family members of classmates) the size of the cake is at 1/2 sheet or full sheet. If I do the full might add the lap pool. At least there is time to make details. Will add photos if I get some over the next week.