A while ago, Mojang added attributes to Minecraft. This feature added a lot of possibilities to custom items rather than just enchantments. In order to get these attributes however, you will need to use Command Blocks or NBT Edit. These effects I will show you are all commands.

To get a Command Block, type in /give @p 137 1.

Boots of Speed

This is the general command to give yourself boots of speed:

/give @p minecraft:leather_boots 1 0 {AttributeModifiers:[{Operation:0,UUIDLe­ast:1,UUIDMost:1,Amount:0.03,AttributeNam­e:generic.movementSpeed,Name:speed}],disp­lay:{Name:"Boots of Speed"}}

This will give you the boots of speed (This command is too long to fit into a chat command, so it must go into a command block).

"/give @p minecraft:leather_boots 1 0": This is the basic give command to give you Leather Boots.

"{AttributeModifiers:[{Operation:0,": This part will verify that it has attributes and the Operation in which to display it.
"Operation:0": Displays as a number (eg."Speed: 100")
"Operation:1": Displays as a percentage (eg."Speed:40%")
ANYTHING ABOVE "Operation:1" WILL CRASH YOUR GAME!

"UUIDLeast:1,UUIDMost:1,": Universal ID (not entirely sure what it means)

"Amount:0.03,": The amplifier of the attribute (in this case an increase of 0.03)

"AttributeName:generic.movementSpeed,Name:Speed}],": Specifies the attribute (in this case Speed)

"display:{Name:"Boots of Speed"}}": renames the item.

All of these parts of the command combine to make Boots of Speed that will increase your speed whilst you're holding or wearing them to double speed.

List of speed increases:
0.01: Between sprinting and walking
0.02: A little less than sprinting
0.03: A little more than sprinting
0.04: A bit more than sprinting
0.05: Almost double the speed of sprinting
0.06: Double speed of sprinting
0.07: A bit more than double speed of sprinting
0.08: Almost 5X regular speed
0.09: 5X regular walking speed
0.10: A bit more than 5X regular walking speed.

(These are not 100% accurate)

Using a negative value will give you slowness. This can be used on a Sword or Armour to make it Heavy. If you decide
to make a SWORD heavy, you will have to add another attribute for the attack damage as the movementSpeed will
overwrite the Attack Damage tag.

I hope this tutorial has helped you!