Here is my home made Dumbbell. I have 2 actually but at the moment one has a collar stuck on it so I cant add weight. I bought 2 20 inch lengths of 1inch Glavanised steel tube. Then after alot of searching managed to find some sleeves that are used for the commercial welded dumbbell handles. After that I purchased a set of shaft collars to secure the plates in place.
The whole lot cost as follows:
Pair 20 inch Glavanised Steel tubes = £20 I think (long time ago)
Pair Knurled Steel Dumbbell Sleeves = £6.50
4 1 inch Shaft Collars = £28 (I actually ordered a set of 10 1 inch Shaft Collars for £70 altogether from fastenal.com without looking for a UK supplier first and got stung big time on the shipping! but I have 6 left over for more dumbbell handles if needed).
So total cost for the handles for me was £54.50, which is extremely expensive I know, but they will hold a ton of weight! using 5kg flat plates, I can get something like 6-7 plates either side. So the dumbbells will most likely go up to 60-70kg (132-154lbs) plus the weight of the bar, sleeve and collars. So its a worthy investment for me!
Here is a pic of one of the dumbbells.