This is a completed engine. No machining or assembly is required. This is our HALO five cylinder radial. The intent was to make an external combustion (steam/compressed air) design that mimicked the operation of real radial aircraft engines as close as possible. It has cams on the crank which operate the pushrods and in turn the rocker arms and the very unique ball bearing valves. The valves are positive sealing on both the exhaust and intake. The more pressure, the tighter they seal. It has five 3/8th inch pistons linked to the single crank via a master rod and connecting rods just as would be expected in a full size radial. Best of all, the design allows you to see nearly every moving part while the engine is running. Even the cams and pushrod end bearings can be seen. Unlike a normal four stroke radial, every piston fires every revolution. Five power strokes per revolution! Some dimensions: .375 pistons with .375 stroke (square engine) The engine is just under 5 inches overall OD The cylinders are .75 inches OD The crankcase is 1.65 OD The Drive shaft is 1/4 Most of the picture are taken of the second prototype. The final form is slightly different as the cylinders bolt on with a square flange as can be seen in the parts picture. Building it: The HALO is Liney Machine's most complex engine. It would be a very good project for someone with a CNC mill but we took great care to ensure that every part can be done on manual equipment. The last picture shown is a halo built by a customer using only a lathe with z-axis. He took gold in a model engeneering show with that engine. We recomend a lathe and mill with rotary table. Sherline and Taig size equipment is excellent. I would rate this as a fairly advanced level project, but with care and patience, I think that a fairly new hobby machinist could build it. With these drawings and a little math you can build a 1,2,3,4, or 5 cylinder version. There are no instructions included with the drawings. How to do the machining and assembly and tuning is up to you. There are lots of assembled views to aide you. As time goes on, I will be writing notes and tips and making them available under the Halo link at the Liney Machine home page. I am also happy to help and answer question via email. Included in the kit are the technical drawings as well as all the hardware and metal you need to to build a complete running engine. This includes machine screws, nuts, pressure fittings, pins, ball bearings, springs, gasket material, and washers. The machine screws included are not the cheap kind you see in most hardware stores. They are high quality fasteners made of stainless steel. All metal will be saw cut from new stock. The Halo uses 112 machine screws in several lengths and head styles plus the other hardware. 191 pieces of hardware total comes sorted in a nice quality plastic tackle box style container. There are also 16 sizes of brass, aluminum, and steel stock. Considering the time and cost to purchase all this in small quantities, the price of the kit is a good value. The designs are included in the kit but can also be purchased separately. They are CAD drawn with clear easy to read dimensions. They come bound in an 8-1/2 x 11 booklet. It has 25 pages. There is an individual drawing of each part as well as several orthographic views showing different parts groupings as they would be in the assembled engine. These views are printed on transparencies so they can be overlaid on each other. This helps in understanding the operating principals, and how the parts are assembled. Please note that these are technical drawings not machining how-to instructions.