How can i join alloy.????

well i am into small radio controled trucks n boats and i want to make a trailer for my truck to pull the boat on i seen an american website that specialy makes trailers but are wanting $400 dollars for one, so no way. i can make a cheeper one its only made from small pieces of alloy shaped like you can find in B&Q or a model shop. but the trailers they make are realy smart looking and have few nuts and bolts holding them together. some parts look like they are soldered i saw a soldering iron in the background of a picture i have heard of alloy welding but this is too small for a welder. they are not glued so how can i fastern these components?? any ideas? thanks regards joe.