Design me a Product

Hi guys, looking for a simple product design drawer. I've come up with a simple idea of creating a universal dumbell connecter and need somebody to just draw this for me. Preferable in 3D but very easy made, so you won't will go back and forward wit it. The project. (Sorry for my english) When you have two dumbells (halters) you want to put them together to get a big halter. An oval tube. Cut open in the middle, attached to eachother with a simpel hinge. Rubber Foam on the inside of the tubes because if the sides of the halters go in, they need to be stuck. Now comes the hard part. Two options! Or you'll need to have a simple adjustable lock where you can easy lock it (without a key or something) till the two dumbells are stuck inside. Or you'll need to make a "wrench" something to keep the two parts stuck. Another thing: please don't make the oval tube whole because if it would be a small halter, it wouldn't fit ofcours. Details: Total length 10-15 cm. Diameter of a normal dumbell 20 cm. Material, probable hard plastic. If possible could you estimate a making price? I'm sorry about the low budget, still a student! :) If I would go trough with this or sell the project i would be glad to give you an extra cut! :)