I posted a wood storage cart on here, based on a design from WWMM. Made from pre used timber heading for the skip. Problem was that I made it 0.9m wide, to save space but then put 1.2m wide sheets on it so no space saved. Here is link to previous post
So I decided to widen it, again using wood scraps. Here is a photo
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The extension bit is on the right, I have now added an insert to get the bin at the same height as the others.
Here is the cart loaded
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I used the wheels I had, 50mm diameter rated at 50 kg each. Even with gentle usage they collapsed. So I upgraded them
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Both from Toolstation. 50mm 50 kg on left cost £3.28 each. On the right, 100mm, 130kg, cost £5.48. The 100mm wheels are much better, easier to move cart and far better value for money.
It is made from a mixture of osb, mdf and ply of different thicknesses (destined for the skip) so it will never be pretty, but it is effective and works well for me.