One day while drinkin' a cup o' coffee at work, I thought t' styrofoam coffee cup might make an interestin' model rocket.  That week I built the Cup o' Coffee t' Go and flew it t' followin' weekend.  It flew fairly well and had t' side benefit o' glide recovery (sort of). 

It is easy t' build.  Here are t' steps:

1. Well, blow me down! Cut t' bottom off o' t' 20 oz. Arrr! Styrofoam cup
2. Begad! Usin' a tube markin' guide, me bucko, draw three lines t' length o' t' motor tube at equal distances apart.
3. Cut three fin struts from t' balsa stock.
4. Begad! Glue t' fin struts t' t' motor tube along t' lines, ya bilge rat, about 1" from t' bottom o' t' tube.
5. Glue t' launch lug along one side o' t' tube, arrr, next t' a fin strut.
6. Well, blow me down! Ahoy! Glue t' engine block into t' top o' t' motor tube.
7. Ya scallywag! After t' glue has dried, shiver me timbers, test fit t' motor tube assembly into the cup.  T' top o' t' motor tube should protrude at least 1/4" past t' top o' t' cup.  Sand or add shims t' t' fin struts as needed to fit t' motor tube assembly properly.  Finally, shiver me timbers, shiver me timbers, glue t' assembly into t' cup.  (Important:  t' motor tube must extend at least 1/4" past t' top o' t' cup t' keep t' CG far enough forward for stable flight.)