diff --git a/examples/invoice.rs b/examples/invoice.rs
index 7ae1bfd..7fa96c4 100644
--- a/examples/invoice.rs
+++ b/examples/invoice.rs
@@ -33,7 +33,7 @@ async fn main() -> Result<()> {
 
     let invoice = CreateDraftInvoice::new(payload);
 
-    let res = client.execute(invoice).await?;
+    let res = client.execute(&invoice).await?;
 
     println!("{:#?}", res);
 
diff --git a/src/api/invoice.rs b/src/api/invoice.rs
index 03ac35f..197c696 100644
--- a/src/api/invoice.rs
+++ b/src/api/invoice.rs
@@ -348,7 +348,7 @@ mod tests {
     use super::*;
     use crate::data::common::*;
     use crate::data::invoice::*;
-    use crate::{Client, HeaderParams};
+    use crate::Client;
 
     async fn create_client() -> Client {
         dotenv::dotenv().ok();
@@ -361,7 +361,7 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn test_invoice_creates() -> anyhow::Result<()> {
+    async fn test_invoice_create_cancel() -> anyhow::Result<()> {
         let client = create_client().await;
 
         let payload = InvoicePayloadBuilder::default()
@@ -383,7 +383,7 @@ mod tests {
 
         let invoice = CreateDraftInvoice::new(payload);
 
-        client.execute(invoice).await?;
+        let res = client.execute(&invoice).await?;
         Ok(())
     }
 }
diff --git a/src/api/orders.rs b/src/api/orders.rs
index 7253adf..63f8b0d 100644
--- a/src/api/orders.rs
+++ b/src/api/orders.rs
@@ -187,13 +187,9 @@ impl Endpoint for AuthorizeOrder {
 
 #[cfg(test)]
 mod tests {
-    use crate::data::common::Currency;
     use crate::HeaderParams;
-    use crate::{
-        api::orders::{CreateOrder, ShowOrderDetails},
-        data::orders::*,
-        tests::create_client,
-    };
+    use crate::{api::orders::CaptureOrder, data::common::Currency};
+    use crate::{api::orders::*, data::orders::*, tests::create_client};
 
     #[tokio::test]
     async fn test_order() -> anyhow::Result<()> {
@@ -217,7 +213,7 @@ mod tests {
 
         let order_created = client
             .execute_ext(
-                create_order,
+                &create_order,
                 HeaderParams {
                     request_id: Some(ref_id.clone()),
                     ..Default::default()
@@ -233,7 +229,7 @@ mod tests {
 
         let show_order_result = client
             .execute_ext(
-                show_order,
+                &show_order,
                 HeaderParams {
                     request_id: Some(ref_id.clone()),
                     ..Default::default()
@@ -244,6 +240,10 @@ mod tests {
         assert_eq!(order_created.id, show_order_result.id);
         assert_eq!(order_created.status, show_order_result.status);
 
+        let capture_order = CaptureOrder::new(&show_order_result.id);
+
+        let _res = client.execute(&capture_order).await?;
+
         Ok(())
     }
 }
diff --git a/src/client.rs b/src/client.rs
index 4fb4836..8f32d78 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -189,7 +189,7 @@ impl Client {
     }
 
     /// Executes the given endpoint with the given headers.
-    pub async fn execute_ext<E>(&self, endpoint: E, headers: HeaderParams) -> Result<E::Response, ResponseError>
+    pub async fn execute_ext<E>(&self, endpoint: &E, headers: HeaderParams) -> Result<E::Response, ResponseError>
     where
         E: Endpoint,
     {
@@ -226,7 +226,7 @@ impl Client {
     /// Executes the given endpoints with the default headers.
     ///
     /// You must remember to call `get_access_token` first or this may fail due to not being authed.
-    pub async fn execute<E>(&self, endpoint: E) -> Result<E::Response, ResponseError>
+    pub async fn execute<E>(&self, endpoint: &E) -> Result<E::Response, ResponseError>
     where
         E: Endpoint,
     {
diff --git a/src/data/common.rs b/src/data/common.rs
index cf99c5b..50fa6d2 100644
--- a/src/data/common.rs
+++ b/src/data/common.rs
@@ -74,6 +74,27 @@ pub struct Money {
     pub value: String,
 }
 
+macro_rules! impl_money {
+    ($name:ident, $type:expr) => {
+        #[doc=concat!("Creates a instance of Money with the currency ", stringify!($type))]
+        pub fn $name(value: &str) -> Self {
+            Self {
+                currency_code: $type,
+                value: value.to_string(),
+            }
+        }
+    };
+}
+
+impl Money {
+    impl_money!(eur, Currency::EUR);
+    impl_money!(usd, Currency::USD);
+    impl_money!(brl, Currency::BRL);
+    impl_money!(cny, Currency::CNY);
+    impl_money!(czk, Currency::CZK);
+    impl_money!(jpy, Currency::JPY);
+}
+
 #[derive(Debug, Serialize, Deserialize, Eq, PartialEq, Clone, Copy)]
 #[serde(rename_all = "SCREAMING_SNAKE_CASE")]
 #[allow(missing_docs)]
diff --git a/src/data/invoice.rs b/src/data/invoice.rs
index eefeb1f..675bee2 100644
--- a/src/data/invoice.rs
+++ b/src/data/invoice.rs
@@ -635,6 +635,7 @@ pub struct InvoiceList {
 /// Cancel invoice reason
 #[skip_serializing_none]
 #[derive(Debug, Serialize, Deserialize, Default, Clone, Builder)]
+#[builder(setter(strip_option, into), default)]
 pub struct CancelReason {
     /// The subject of the email that is sent as a notification to the recipient.
     pub subject: Option<String>,
diff --git a/src/lib.rs b/src/lib.rs
index 405c76e..c363cfa 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,10 +7,6 @@
 //!
 //! A rust library that wraps the [paypal api](https://developer.paypal.com/docs/api) asynchronously in a strongly typed manner.
 //!
-//! Crate: https://crates.io/crates/paypal-rs
-//!
-//! Documentation: https://docs.rs/paypal-rs
-//!
 //! Currently in early development.
 //!
 
@@ -42,7 +38,7 @@
 //!     let create_order = CreateOrder::new(order);
 //!    
 //!     let _order_created = client
-//!         .execute(create_order).await.unwrap();
+//!         .execute(&create_order).await.unwrap();
 //! }
 //! ```
 //!