Flexible Man Cave Storage Ideas
You have cool stuff that took time and money to collect. You need good man cave storage where you can store this collection of stuff between bouts of use.
Where do you store them?
The collection might consist of tools, something that tools get used on, or something you bought for more fun. You need suitable man cave storage to keep it dry.
Collections shouldn't look like this!

The above situation needs a storage solution with stuff piled across the bench. It's going to be a problem to find the tool you need. Usually the storage solution will depend on what needs to be stored.
Solution Organised Storage
If your stuff can be hung on a wall of hooks and clips as displayed below then they will be easier to see and you can find the tools. There’s less of a problem finding the tools when you put them on display (until you run out of wall space).

Garden sheds are a common small storage solution for small yards and units. Here is where you can shelter your man cave storage items. Use the wall space for hanging tools and make some room for cabinets and a bench. You can pull out items held in cabinet storage when needed, use them and put them away to keep the work area usable.

Internal areas of a shed can be large as below or small as above. Develop any internal space to be efficient with a combination of storage solutions. Use whatever of the limited internal space is available. No one else is going in there.
The shed may need to incorporate a bench with a power bar linked into the house. You need power for using electric tools at the bench. While working in the shed ventilate the area by fan. A cheaper option is to hold the doors open.

Use the areas under benches and along walls to hold compact storage containers. Those can be wood, plastic or metal boxes for tools and equipment. Pull the box out, find your items and use them. After, return to storage when they're no longer required.
Man Cave Storage Shelving Ideas
A lot of your stuff will fit into organised cabinet style room storage units. Use timber, metal and plastic boxes in under-bench storage. Use shelves in a partitioned cabinet. Install overhead cupboards along the sides of a shed and put organiser trays on the shelves.
But there’s no big problem in the man cave store until the wall space runs out. Then reconfigure it for more storage space, or the solution may be to get that larger shed you wanted.
Arrange your essential electrical tools and their associated attachments in woven cane baskets. You can use wooden draws, plastic boxes and organised them on storage shelves. Slide items into shelves of a fixed wall storage system. A free standing cupboard recycled from another use would be ideal at one end of the shed. Try installing a commercial racking set in the bigger shed.

Organize your storage shelves so you can see where electric power tools are so you can use them. You need to return them to the shelf when you complete the job to keep the system working.
Organize smaller bits and pieces associated with your tools in a partitioned cabinet. Have draws labelled like this one below. Depending on space you could stack the bank of draws along the side of a shed.
Leave small consumable items in store packaging. Put them in labelled organiser drawers so it's easier finding them. For added space, combine similar boxed items into the draws.

Organize your reticulation and plumbing items in a cabinet. Use plastic drawers like this one. They will be easier to find with open spacing if you set it up like this below.

If the space is tight space the banks of drawers and organise them in size. Try screwing each tray in lines onto a sheet of plywood. Label your baskets. It will save time when re-stocking shelves with consumable material for your project.
Plan Storage Ideas: Measure and Fit
When you design areas for storage it pays to measure the areas with accuracy. You need to calculate sizing to be sure that everything will fit in the space. Remember to check the access pathway. Note the shed's door size before buying anything going inside the shed. You may need to re-fabricate your shelving, racking or your bench after delivery. Try to install shelves with flat pack component parts inside the shed.
Take measurements to ensure what you buy will fit into the space available.