diff --git a/dfdx-nn-derives/src/lib.rs b/dfdx-nn-derives/src/lib.rs
index b30e4833..effe281b 100644
--- a/dfdx-nn-derives/src/lib.rs
+++ b/dfdx-nn-derives/src/lib.rs
@@ -8,6 +8,81 @@ macro_rules! has_attr {
     };
 }
 
+/// Allows you to implement [dfdx_nn::Module], while automatically implementing the following:
+/// 1. [dfdx_nn::BuildOnDevice]
+/// 2. [dfdx_nn::ResetParams]
+/// 3. [dfdx_nn::UpdateParams]
+/// 4. [dfdx_nn::ZeroGrads]
+/// 5. [dfdx_nn::SaveSafeTensors]
+/// 6. [dfdx_nn::LoadSafeTensors]
+///
+/// If your struct contains sub module configs, then you must add the `#[module]` attribute to those items. Any field that is marked with `#[module]` will be expected to implement [dfdx_nn::BuildOnDevice].
+///
+/// You can control the name of the built struct with the `#[built(<type name>)]` attribute on the struct.
+///
+/// # Using CustomModule on unit structs
+///
+/// Here we have a unit struct that just calls a method on Tensor in the forward:
+///
+/// ```rust
+/// # use dfdx_nn::*;
+/// # use dfdx::prelude::*;
+/// #[derive(Default, Debug, Clone, Copy, CustomModule)]
+/// pub struct Abs;
+/// impl<S: Shape, E: Dtype, D: Device<E>, T: Tape<E, D>> Module<Tensor<S, E, D, T>> for Abs {
+///     type Output = Tensor<S, E, D, T>;
+///     type Error = D::Err;
+///     fn try_forward(&self, x: Tensor<S, E, D, T>) -> Result<Self::Output, Self::Error> {
+///         x.try_abs()
+///     }
+/// }
+/// ```
+///
+/// # Using CustomModule on structs with non-parameter fields
+///
+/// ```rust
+/// # use dfdx_nn::*;
+/// # use dfdx::prelude::*;
+/// #[derive(Default, Debug, Clone, Copy, CustomModule)]
+/// pub struct Reshape<S: Shape>(pub S);
+///
+/// impl<Src: Shape, Dst: Shape, E: Dtype, D: Device<E>, T: Tape<E, D>> Module<Tensor<Src, E, D, T>>
+///     for Reshape<Dst>
+/// {
+///     type Output = Tensor<Dst, E, D, T>;
+///     type Error = D::Err;
+///     fn try_forward(&self, x: Tensor<Src, E, D, T>) -> Result<Self::Output, Self::Error> {
+///         x.try_reshape_like(&self.0)
+///     }
+/// }
+/// ```
+///
+/// # Using CustomModule on structs with sub modules
+///
+/// Here there are a couple things to note:
+/// 1. We must use the `#[built(<type name>)]` to control the name of the actual built struct
+/// 2. We must use that type name when implementing `Module`
+/// 3. We must annotate the sub module with `#[module]`
+///
+/// ```rust
+/// # use dfdx_nn::*;
+/// # use dfdx::prelude::*;
+/// #[derive(Debug, Clone, CustomModule)]
+/// #[built(ResidualMatMul)]
+/// pub struct ResidualMatMulConfig<I: Dim, O: Dim>(#[module] pub matmul: MatMulConfig<I, O>);
+///
+/// impl<X: WithEmptyTape, I: Dim, O: Dim, E: Dtype, D: Device<E>> Module<X> for ResidualMatMul<I, O, E, D>
+/// where
+///     MatMul<I, O, E, D>: Module<X, Output = X>,
+///     X: TryAdd<X, Output = X>,
+/// {
+///     type Output = X;
+///     type Error = D::Err;
+///     fn try_forward(&self, x: X) -> Result<Self::Output, Self::Error> {
+///         self.matmul.try_forward(x.with_empty_tape())?.try_add(x)
+///     }
+/// }
+/// ```
 #[proc_macro_derive(CustomModule, attributes(module, built))]
 pub fn custom_module(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
     let input = parse_macro_input!(input as DeriveInput);