Purchased a Horizon model of the Mercury-Atlas and planning to convert it to a flying model. Just started nutting out how I’m going to do this. Have down sized the diameter on a tube from a parchment paper dispenser to fit inside the atlas plastic tube. This should protect the plastic from the hot ejection charge. Still have to glue this together. Glued together the lower section of the model and cut an opening thru for the engine mount. Using ideas from Peter Always model rocketry book on constructing the engine mount and plastic fins.