diff --git a/src/bad_things.rs b/src/bad_things.rs
new file mode 100644
index 0000000..d5bc526
--- /dev/null
+++ b/src/bad_things.rs
@@ -0,0 +1,50 @@
+// use std::{fmt::Debug, intrinsics::transmute, mem::{transmute_copy, MaybeUninit, ManuallyDrop}, alloc::{dealloc, Layout}, ptr::drop_in_place};
+
+// trait IsSized {
+//     type SizedRepr;
+
+//     fn is_sized() -> bool;
+// }
+
+// impl<T: ?Sized> IsSized for T {
+//     default type SizedRepr = Box<T>;
+
+//     default fn is_sized() -> bool {
+//         false
+//     }
+// }
+
+// impl<T> IsSized for T {
+//     type SizedRepr = T;
+
+//     fn is_sized() -> bool {
+//         true
+//     }
+// }
+
+// #[repr(transparent)]
+// struct Item<T: ?Sized>(<T as IsSized>::SizedRepr);
+
+// impl<T: ?Sized> Item<T> {
+//     fn from_box(v: Box<T>) -> Self {
+//         let ret = if T::is_sized() {
+//             // SAFETY: #[repr(transparent)], and we know its `SizedRepr` is just `T`
+//             unsafe { (&*v as *const _ as *const Self).read() }
+//             let ptr = Box::into_raw(v);
+//             unsafe { dealloc(ptr.cast(), Layout::for_value_raw(ptr)) }
+//         } else {
+//             // SAFETY: #[repr(transparent)], and we know its `SizedRepr` is `Box<T>`
+//             unsafe { (&v as *const _ as *const Self).read() }
+//             mem::forget(v);
+//         };
+
+//         ret
+//     }
+// }
+
+// #[test]
+// pub fn testing() {
+//     dbg!(usize::is_sized());
+//     dbg!(<dyn Debug>::is_sized());
+// }
+
diff --git a/src/ptr_ext.rs b/src/ptr_ext.rs
new file mode 100644
index 0000000..5537f62
--- /dev/null
+++ b/src/ptr_ext.rs
@@ -0,0 +1,170 @@
+use std::{ptr::{self, Pointee}, mem::size_of_val_raw, alloc::{alloc, Layout}};
+
+use self::__priv::Sealed;
+
+mod __priv {
+    pub trait Sealed {}
+
+    impl<T: ?Sized> Sealed for *const T {}
+    impl<T: ?Sized> Sealed for *mut T {}
+}
+
+pub trait PtrExt: Sealed {
+    type Pointee: ?Sized;
+
+    fn addr(self) -> usize;
+
+    fn align_up(self, align: usize) -> Self;
+
+    fn with_addr_from<U: ?Sized>(self, addr: *const U) -> Self;
+
+    fn with_addr(self, addr: usize) -> Self;
+
+    unsafe fn get_end(self) -> Self;
+
+    fn add_bytes(self, offset: usize) -> Self;
+
+    fn sub_bytes(self, offset: usize) -> Self;
+
+    unsafe fn copy_bytes_to<U: ?Sized>(self, dest: *mut U, count: usize);
+
+    unsafe fn copy_val_to<U: ?Sized>(self, dest: *mut U);
+
+    unsafe fn read_to_box(self) -> Box<Self::Pointee>;
+}
+
+impl<T: ?Sized> PtrExt for *const T {
+    type Pointee = T;
+
+    fn addr(self) -> usize {
+        self.to_raw_parts().0 as usize
+    }
+
+    fn align_up(self, align: usize) -> Self {
+        self.with_addr((self.addr() + align - 1) & !(align - 1))
+    }
+
+    fn with_addr_from<U: ?Sized>(self, addr: *const U) -> Self {
+        self.with_addr(addr.addr())
+    }
+
+    fn with_addr(self, addr: usize) -> Self {
+        ptr::from_raw_parts(addr as _, self.to_raw_parts().1)
+    }
+
+    unsafe fn get_end(self) -> Self {
+        self.add_bytes(size_of_val_raw(self))
+    }
+
+    fn add_bytes(self, offset: usize) -> Self {
+        self.with_addr_from(self.cast::<u8>().wrapping_add(offset))
+    }
+
+    fn sub_bytes(self, offset: usize) -> Self {
+        self.with_addr_from(self.cast::<u8>().wrapping_sub(offset))
+    }
+
+    unsafe fn copy_bytes_to<U: ?Sized>(self, dest: *mut U, count: usize) {
+        self.cast::<u8>().copy_to(dest.cast(), count);
+    }
+
+    unsafe fn copy_val_to<U: ?Sized>(self, dest: *mut U) {
+        self.copy_bytes_to(dest, size_of_val_raw(self));
+    }
+
+    unsafe fn read_to_box(self) -> Box<Self::Pointee> {
+        let alloc = alloc(Layout::for_value_raw(self));
+        self.copy_val_to(alloc);
+        Box::from_raw(alloc.with_meta_from(self))
+    }
+}
+
+impl<T: ?Sized> PtrExt for *mut T {
+    type Pointee = T;
+
+    fn addr(self) -> usize {
+        self.to_raw_parts().0 as usize
+    }
+
+    fn align_up(self, align: usize) -> Self {
+        self.with_addr((self.addr() + align - 1) & !(align - 1))
+    }
+
+    fn with_addr_from<U: ?Sized>(self, addr: *const U) -> Self {
+        self.with_addr(addr.addr())
+    }
+
+    fn with_addr(self, addr: usize) -> Self {
+        ptr::from_raw_parts_mut(addr as _, self.to_raw_parts().1)
+    }
+
+    unsafe fn get_end(self) -> Self {
+        self.add_bytes(size_of_val_raw(self))
+    }
+
+    fn add_bytes(self, offset: usize) -> Self {
+        self.with_addr_from(self.cast::<u8>().wrapping_add(offset))
+    }
+
+    fn sub_bytes(self, offset: usize) -> Self {
+        self.with_addr_from(self.cast::<u8>().wrapping_sub(offset))
+    }
+
+    unsafe fn copy_bytes_to<U: ?Sized>(self, dest: *mut U, count: usize) {
+        self.cast::<u8>().copy_to(dest.cast(), count);
+    }
+
+    unsafe fn copy_val_to<U: ?Sized>(self, dest: *mut U) {
+        self.copy_bytes_to(dest, size_of_val_raw(self));
+    }
+
+    unsafe fn read_to_box(self) -> Box<Self::Pointee> {
+        let alloc = alloc(Layout::for_value_raw(self));
+        self.copy_val_to(alloc);
+        Box::from_raw(alloc.with_meta_from(self))
+    }
+}
+
+pub trait ConstPtrExt: Sealed {
+    fn data_ptr(self) -> *const ();
+
+    fn with_meta<U: ?Sized>(self, meta: <U as Pointee>::Metadata) -> *const U;
+
+    fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *const U;
+}
+
+impl<T: ?Sized> ConstPtrExt for *const T {
+    fn data_ptr(self) -> *const () {
+        self.to_raw_parts().0
+    }
+
+    fn with_meta<U: ?Sized>(self, meta: <U as Pointee>::Metadata) -> *const U {
+        ptr::from_raw_parts(self.data_ptr(), meta)
+    }
+
+    fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *const U {
+        self.with_meta(ptr.to_raw_parts().1)
+    }
+}
+
+pub trait MutPtrExt: Sealed {
+    fn data_ptr(self) -> *mut ();
+
+    fn with_meta<U: ?Sized>(self, meta: <U as Pointee>::Metadata) -> *mut U;
+
+    fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *mut U;
+}
+
+impl<T: ?Sized> MutPtrExt for *mut T {
+    fn data_ptr(self) -> *mut () {
+        self.to_raw_parts().0
+    }
+
+    fn with_meta<U: ?Sized>(self, meta: <U as Pointee>::Metadata) -> *mut U {
+        ptr::from_raw_parts_mut(self.data_ptr(), meta)
+    }
+
+    fn with_meta_from<U: ?Sized>(self, ptr: *const U) -> *mut U {
+        self.with_meta(ptr.to_raw_parts().1)
+    }
+}
\ No newline at end of file